Marine Protected Area - Fisheries Guidance Note

Basking shark (Cetorhinus maximus)

Conservation status: ICUN red list as Vulnerable (Worldwide) and Endangered (North East Atlantic).

Fisheries interactions: Potential incidental catch or entanglement in fishing gear

MPA Network: Sea of Hebrides Nature Conservation pMPA.

Wider seas: Mostly seen on the West coast of Scotland in summer but can be seen round the whole of the Scottish coast. Protection: OSPAR Annex V, Wildlife & Countryside Act 1981 (as amended by the Nature Conservation (Scotland) Act 2004), UK BAP, Scottish Biodiversity Strategy, PMF.

Protection: OSPAR Annex V, Wildlife & Countryside Act 1981 (as amended by the Nature Conservation (Scotland) Act 2004), UK BAP, Scottish Biodiversity Strategy, PMF.

The basking shark, Cetorhinus maximus is the largest fish to visit British waters¹ they have a near global distribution within the coastal and continental waters of northern and southern temperate zones², however, it is thought that significantly important areas for basking sharks exist in Scottish waters^3,4. 

Basking sharks are found in Scottish coastal waters in the summer, following thermal fronts in order to feed. Peak observations recorded in Scotland are between June and October, particularly during July and August^3,5.  The islands of Hyskeir and Canna in the Sea of Hebrides and the island of Coll and Tiree have been identified as hotspots for basking shark abundance and modelling work has shown they persistently occur in numbers above mean densities in the same areas^3,6. Sharks show seasonal residency within the Sea of the Hebrides, and return to the same coastal waters in following years (Doherty et al 2017). In October, basking sharks move to deeper water, with some remaining in UK waters and others migrating further south to the Bay of Biscay or the Azores. 

The ability of basking sharks to recover from physical damage such as collisions or entanglement is unknown, however like many elasmobranchs, they are highly susceptible to exploitation and population declines due to their slow growth rates, long maturation time, long gestation period and low fecundity⁷ 

Basking sharks are known to encounter a variety of gears including, gill nets, trawl nets and buoy ropes (raisers) of static gear. There are anecdotal accounts of entanglements and incidental catch throughout Scotland, although the extent to which this happens is unknown⁵.

Basking sharks are susceptible to collision from fishing vessel movement, especially while they are at the surface during the summer months. 

Impacts

All fishing vessels

Basking sharks are most at risk from collisions with fishing vessels during the summer months when greater numbers of animals are at the surface feeding and engaged in courtship-like behaviour at the surface¹. This is most likely to occur on the West coast of Scotland especially in the sea of Hebrides around Coll, Tiree, and the Small Isles, as this is where large numbers aggregate making them more vulnerable⁸. There is evidence of basking sharks with injuries that could have been caused by collision with boat propellers. Underwater noise and close physical presence of fishing vessels may cause disturbance, basking sharks that have been disturbed may reduce time feeding or move to other areas. The effects of disturbance may impact the shark’s energetic needs and ultimately affect reproductive success, and reduce resilience to environmental pressures⁹ (e.g. predation, infection, climate change).  

All towed gears (including pelagic and demersal gears) 

There are records of incidental catch of basking sharks in towed gears in the UK and worldwide^5,10,15. However, the frequency of such encounters is currently unknown.  

A study from a trawl fishery in New Zealand provides an indication that the headline height (distance of net from seabed) may be an important factor affecting basking shark catch rates¹⁰. The study showed a notable increase in incidental capture in water depth of 200400m with a headline height greater than 4m.

All static gears (including drift nets, gillnets, trammel nets, longlines, pots and traps)

There is a risk of entanglement in the ropes of creels/pots and static nets during August and September when the basking sharks are present in large aggregations and engaged in feeding and social behaviours¹. Scottish Marine Animal Stranding Scheme (SMASS) and the Marine Conservation Society (MCS) have records of a basking shark being caught in creel ropes^5,11, the existing data is likely to reflect under-reporting. There is evidence from  New Zealand that basking sharks can become entangled in other static gears. There is a reported incident of juvenile basking sharks entangled in surface drift nets, while adults have been reported entangled in bottom set nets¹⁰.

The Scottish creel fishing industry recognizes entanglement as a potential issue and is working in partnership with scientists, NGO’s and government to understand the issue. The Scottish Entanglement Alliance (SEA) was formed with the support of the European Maritime Fisheries Fund to engage with the Scottish inshore creel fishing fleet to better understand the incidence of marine animal entanglements, and to develop sustainable and proportional mitigation strategies. SEA have developed, with industry, a best practice guide including methods to setting creels for reducing the risk of entanglement.

Marine Scotland have recently reviewed their under 12m fishing vessel reporting form (FISH1) which includes a place for reporting bycatch and entanglements. This new reporting method should help to improve our understanding of the issue. 

NatureScot Advice

All fishing vessels - The potential for disturbance could be mitigated by the same best practice as laid out for vessels in the Scottish Marine Wildlife Watching Code. This would require vigilance when travelling or fishing within the MPA, and reducing vessel speed when basking sharks are present in proximity.

All towed gear – the development and adoption of best practice to reduce or limit the risk of incidental catch of basking sharks should be considered.

All static gear – Exclusion of the use of drift nets and nets set on the seabed (tangle, trammel, gill) to avoid the risk of entanglement/bycatch of basking sharks between April and October due to the risk of entanglement is recommended. 

The Scottish Entanglement Alliance (SEA) has produced a best practice guide for setting creels and should be followed to reduce the risk of entanglement¹². The guide encourages fishers to reduce the amount of floating line in the water column to minimise the risk of entanglement and encourages reporting any entangled animals alive or dead. 

Confidence in advice

All fishing vessels – Medium certainty –there is published research associated with vessel collision and disturbance for wildlife watching boats, however the relevance of this to fishing vessels needs to be considered further. 

All towed gears - Medium certainty – there is published data for other countries reporting incidental capture of basking sharks in towed gear, but very little data from Scottish waters. Incidents of capture in towed gear in the UK have been reported in grey literature but the extent of incidental captures is unknown. 

All static gears – Medium certainty – there is published data for other countries reporting incidental capture of basking sharks in static gear, but very little data from Scottish waters. Incidents of capture in creel ropes and static nets in the UK have been reported in grey literature but the extent of incidental captures is unknown.  

Evidence

¹Lancaster et al. 2014; ²Nicholson et al, 2000; ³Speedie et al, 2009; ⁴SNH, 2012; ⁵Bloomfield & Solandt, 2008 ; ⁶Francis & Duffy, 2002; ⁷Earll, 1993 ; ⁸Doherty et al, 2017 ; ⁹Galpin, 2009. ¹⁰Francis, 2017; ¹¹strandings.org/cgi-bin/map.pl; ¹² Scottish Creel Fishermens Federation; ¹⁷Paxton et al, 2014

• Directly relevant peer reviewed literature – yes
• Directly relevant grey literature – yes
• Inference from peer reviewed or grey literature relating to a comparable habitat, gear or geographical area. – yes
• Expert judgement -

References:

Bloomfield, A. & Solandt, J.L. 2008. The Marine Conservation Society Basking Shark Watch Project: 20 year report (1987-2006). Marine Conservation Society Report, Ross on Wye, UK.

Doherty P.D. , J.M. Baxter, B.J. Godley, R.T. Graham, G. Hall, J. Hall, L.A. Hawkes, S.M. Henderson, L. Johnson, C. Speedie, M.J. Witt. 2017. Testing the boundaries: Seasonal residency and inter-annual site fidelity of basking sharks in a proposed Marine Protected Area. Biological Conservation Vol209, 68-75.

Earll, R.C. 1993. Shark & Ray Fisheries with particular reference to Scotland. A report to Scottish Natural Heritage from the Marine Conservation Society.

Francis, M. 2017. Review of commercial fishery interactions and population information for New Zealand basking shark. National Institute of Water and Atmospheric Research. 

Francis, M & Duffy, C. 2002. Distribution, seasonal abundance and bycatch of basking sharks (Cetorhinus maximus) in New Zealand, with observations on their winter habitat. Marine Biology; 140: 831-842. DOI 10. 1007/s00227-001-0744-y

Galpin, J. Land based observation of unusual basking shark behaviour and responses to disturbance, Dalby Point, Isle of Man, 1995 to 2009. Basking sharks - a global perspective: conservation, management and research. Unpublished conference abstract, Isle of Man, 2009.

Lancaster, J. (Ed.), McCallum, S., Lowe A.C., Taylor, E., Chapman A. & Pomfret, J. (2014). Development of detailed ecological guidance to support the application of the Scottish MPA selection guidelines in Scotland’s seas. Scottish Natural Heritage Commissioned Report No.491.

Nicholson, D., Harris, E. & Pollard, S. 2000. The Location and Usage of Sites in Scotland by the Basking Shark (Cetorhinus maximus). Scottish Natural Heritage Commissioned Report No. F99AA402

Paxton, C.G.M., Scott-Hayward, L.A.S. and Rexstad, E. (2014). Statistical approaches to aid the identification of Marine Protected Areas for minke whale, Risso’s dolphin, white-beaked dolphin and basking shark. Scottish Natural Heritage Commissioned Report No. 594. 

SNH, 2012. Marine Protected Areas and basking sharks (Cetorhinus maximus). A position paper produced for the 4th MPA stakeholder Workshop, Heriot-Watt University, 14-15 March 2012. Produced by Scottish Natural Heritage for the Scottish MPA Project.

Speedie, C.D., Johnson, L.A. & Witt, M.J. 2009. Basking shark hotspots on the west coast of Scotland: Key sites, threats and implications for the conservation of the species. Scottish Natural Heritage Commissioned report No. 339

Minke whale (Balaenoptera acutorostrata)

Conservation status: ICUN red list as Least Concern

Fisheries interactions: Potential catch or entanglement in fishing gear. Connectivity to fisheries for prey, including herring, sprat, and sandeel.

MPA Network: Southern Trench Nature Conservation pMPA and Sea of Hebrides Nature conservation pMPA

Wider seas: Present worldwide. Commonly seen throughout Scottish waters and is the strong hold for Europe.

Protection: European Protected Species (EPS), UK Biodiversity Action Plan (UK BAP), Priority Marine Feature (PMF).

The minke whale is the most common baleen (toothless) whale both in the North Atlantic and around the British Isles. Seasonal and inter-annual variation in abundance has been linked to variation in oceanographic conditions and prey availability^1,2. Minke whales feed on krill, sandeels, and other schooling fish such as herring and sprat³. Minke whales are usually seen singly or in pairs, although they sometimes aggregate into larger groups of around 1020 individuals when feeding^4,5. Minke whales have a sharply pointed snout and are easily identified by a white band on each pectoral fin. They are the smallest baleen whales seen in Scottish waters. 

Impacts

All fishing vessels

Disturbance to minke whales can be caused by both vessel presence and vessel noise. Repeated or extended disturbance can result in extra expenditure of energy, masking of communication, disruption to social interactions, and a decrease in foraging activity. A reduction in feeding success could lead to a decrease in energy availability for foetal development and nursing, resulting in reduced calving rates. By altering calving rates and affecting long-term growth and survival rates of individuals, disturbance can have population level impacts.  

Their smaller size affects their ability to survive if they become entangled in fishing gears; once entangled they have limited strength and stamina to surface and breath. Entangled minke whales are less likely to survive an entanglement so any rescue attempts must be made quickly in comparison to other larger whales e.g. humpback whales or pilot whales.

All towed gears (including pelagic and demersal gears - beam trawl, otter trawl, hydraulic and scallop dredges)

Incidental capture of minke whale with bottom trawls and purse seine nets have been reported⁶, however the frequency of such encounters is currently unknown. Activities with the potential to cause significant degradation or abrasion to the seabed, such as towed demersal fishing gear have the potential to influence the structure and function of habitat essential for sandeel and herring life stages. These fish species are key prey for minke whale.

Sandeel habitat (i.e. sandy sediments) are sensitive to activities that cause such disruption to the sediment that they can no longer support sandeels. With respect to fishing, only hydraulic fishing methods are likely to be capable of such disruption (although such gear is generally limited to relatively shallow waters). Other towed gears are of less concern as they are unlikely to cause sufficient abrasion to alter the sediment character and prevent sandeels living in it. 

Herring spawning grounds are sensitive to anthropogenic activity such as dumping of dredge spoil, extraction of marine aggregates (e.g. gravel and sand) and erection of structures in close proximity⁷ Fishing with towed gears and hydraulic methods have the potential to cause disruption to the herring eggs and the spawning habitat. Herring gather on spawning grounds and spawn more or less simultaneously, sticky eggs are released in a single batch onto coarse sand and gravel. The eggs take around 3 weeks to hatch⁸, during this time they are sensitive to all fishing activity that contact the seabed.

A reduction in prey items from important feeding areas has the potential to reduce or change the types of prey available to minke whales.  Minke whales are sensitive to prey depletion and this has the potential to negatively affect them. It is unknown to what degree minke whales are able to respond to a reduction in prey, e.g. through prey switching or moving to new foraging areas, although given the range of prey species they eat there is potential for them to switch.

All static gears (including drift nets, gillnets, trammel nets, longlines, pots and traps)

Globally, fishing gear entanglement is considered the greatest risk to minke whales⁹. Evidence shows that the majority of entanglements are caused by gill nets and creels⁸. Photographic records report that 18% of minke whales on the west coast of Scotland show evidence of previous entanglement, the head and the body regions are most commonly scarred¹⁰. 

For baleen whales caught in static gears (including creels, pots, traps, and nets), the most common part of the gear associated with animal entanglement is the buoy line (33%) followed by the groundline (16%)¹¹. Mortality rates for trapped minke whales is 77%¹⁰, however this estimate is largely based on interactions with fish traps in Newfoundland¹². Entanglement though appears to represent the single most frequently-documented cause of mortality for minke whales in Scottish waters (based on Scottish Marine Animal Stranding Scheme data 2012-2017).

The Scottish creel fishing industry recognizes entanglement as a potential issue and is working in partnership with scientist, NGO’s and government to understand the issue. The Scottish Entanglement Alliance (SEA) was formed with the support of the European Maritime Fisheries Fund to engage with the Scottish inshore creel fishing fleet to better understand the incidence of marine animal entanglements, and to develop sustainable and proportional mitigation strategies. SEA have developed, with industry, a best practice guide including methods to setting creels for reducing the risk of entanglement.

Marine Scotland have recently reviewed their under 12m fishing vessel reporting form (FISH1) which includes a place for reporting bycatch and entanglements. This new reporting method should help to improve our understating of the issue. 

NatureScot advice

All fishing vessels – The potential for disturbance could be mitigated by the same best practice as laid out for vessels in the Scottish Marine Wildlife Watching Code. This would require vigilance when travelling or fishing within the MPA, and reducing vessel speed when minke whales are present in proximity.

All towed gear – As there is little direct interaction between minke whales and towed gear fisheries, no management measures are suggested. 

Measures ensuring that fishing activity does not prevent or disrupt the availability of key prey species (e.g. herring, sprat) for minke whale are recommended. 

The exclusion of targeted fishing for sandeels is recommended because of the importance of sandeels as a prey species for minke whales. 

The exclusion of hydraulic fishing methods from the habitat of sandeels grounds (as a key prey species of minke whale) within an MPA is recommended.

Measures ensuring that fishing activity does not prevent or disturb herring spawning or remove herring eggs is recommended during spawning periods at known locations within MPA as a precautionary measure to improve herring stocks.

All static gear – Exclusion of the use of drift nets and nets set on the seabed (tangle, trammel, gill) between April to October due to the risk of entanglement/incidental capture of minke whales is recommended. 

The Scottish Entanglement Alliance (SEA) has produced a best practice guide for setting creels and should be followed to reduce the risk of entanglement¹⁴. The guide encourages fishers to reduce the amount of floating line in the water column to minimise the risk of entanglement and encourages reporting any entangled animals alive or dead. 

Confidence in advice

All fishing vessels – Medium certainty –there is published research associated with vessel collision and disturbance for wildlife watching boats, however the relevance of this to fishing vessels needs to be considered further. 

All towed gear – Medium certainty – there is grey literature on the direct effects of incidental capture of minke whales. Predator – prey relationship between minke whale and key food species, herring and sandeels is an unresearched area with no directly relevant evidence.

All static gear – High certainty. Published literature on activity and receptor. This issue is under-reported so the extent of minke whale entanglement is unknown in Scottish waters. A project lead by SNH (Scottish Entanglement Alliance) is investigating entanglement and is due to report in 2020. 

Evidence

¹Tetley et al., 2008; ²Anderwald et al., 2012; ³Pierce et al., 2004; ⁵Evans et al., 2003; ⁶Reid et al.,2003; ⁶ICES 2018; ⁷Scottish government website; ⁸song et al. 2010; ⁹van der Hoop et al., 2012 ¹⁰Mathewson, 2012; ¹¹Johnson et al., 2005;¹²Perkins & Beamish, 1979;¹³Northridge et al., 2010;  ¹⁴SEA best practice guide.  

• The peer reviewed literature suggests that there is an interaction between minke whales and fishing gear through entanglement, however no evidence exists for the significance of this impact at a population level. Evidence on causes of death of entangled minke whales is from studies carried out in the USA. General mitigation information on baleen whales in USA and Australia. The grey literature (government reports and honours dissertations) provides information on the interaction between minke whales and creel fishing in the UK.
• Directly relevant peer reviewed literature – yes
• Directly relevant grey literature  - yes
• Inference from studies on comparable habitats, gears or geographical areas. – yes
• Expert judgement or anecdotal evidence  - yes

References

Anderwald, P., Evans, P.G.H., Dyer, R., Dale, A., Wright, P.J. & Hoelzel, A.R. 2012. Spatial scale and environmental determinants in minke whale habitat use and foraging. Marine Ecology Progress Series 450: 259 – 274.

Cassoff, R. M., Moore, K. M., McLellan, W. A., Barco, S. G., Rotstein, D. S., & Moore, M. J.

(2011). Lethal entanglement in baleen whales. Diseases of Aquatic Organisms 96: 175–185

Department of Fisheries (2012) Application to the Department of Sustainability, environment, water, population and communities on the Western Rock Lobster Fishery. Appendix 2.

Government of Western Australia.

Evans, P.G.H., Anderwald, P. & Baines, M.E. 2003. UK Cetacean Status Review. Final Report to English Nature & Countryside Council for Wales. Sea Watch Foundation, Oxford, UK. 150pp.

Johnson, A., Salvador, G., Kenney, J., Robbins, J., Kraus, S., Landry, S., & Clapham, P. (2005). Fishing gear involved in entanglements of right and humpback whales. Marine Mammal Science 21(4): 635-645.

ICES 2018 report 

Mathewson, F. 2012. Non-lethal entanglement of minke whales (Balaenoptera acutorostrata) in fishing gear in the Hebrides. BSc thesis. University of St Andrews. 38pp.

McCarron, P. & Tetreault, H. (2012) Lobster Pot Gear Configurations in the Gulf of Maine.

Northridge, S., Cargill, A., Coram, A., Mandleberg, L., Calderan, S.,  Reid. R. 2010 Entanglement of minke whales in Scottish waters; an investigation into occurrence, causes and mitigation. SMRU Contract report to Scottish Government.

Perkins, J. S., & Beamish, P. C. 1979. Net entanglements of baleen whales in the inshore fishery of Newfoundland. Journal of the Fisheries Board of Canada 36(5): 521-528.

Pierce, G.J., Santos. M.B., Reid. R.J., Patterson. I.A.P. & Ross. H.M. 2004. Diet of minke whales Balaenoptera acutorostrata in Scottish (UK) waters with notes on strandings of this species in Scotland 1992–2002. Journal of the Marine Biological Association of the UK 84: 1241–1244.

Reid, J.B., Evans, P.G.H. & Northridge, S.P. 2003. Atlas of Cetacean Distribution in Northwest European Waters. Joint Nature Conservation Committee, Peterborough. 76pp.

Scottish Government website

Song, K. J., Kim, Z. G., Zhang, C. I., & Kim, Y. H. 2010. Fishing gears involved in entanglements of minke whales (Balaenoptera acutorostrata) in the East Sea of Korea. Marine Mammal Science 26(2): 282-295.

Tetley, M.J., Mitchelson-Jacob, E.G. & Robinson, K.P. 2008. The summer distribution of coastal minke whales (Balaenoptera acutorostrata) in the southern Moray Firth, northeast Scotland, in relation to co-occurring mesoscale oceanographic features. Remote Sensing of Environment 112: 3449-3454.

Van Der Hoop, J. M., Moore, M. J., Barco, S. G., Cole, T. V., Daoust, P. Y., Henry, A. G., & Solow, A. R. (2013). Assessment of management to mitigate anthropogenic effects on large whales. Conservation Biology 27(1): 121-133.

Volgenau, L., Kraus, S. D., & Lien, J. (1995). The impact of entanglements on two substocks of the western North Atlantic humpback whale, Megaptera novaeangliae. Canadian Journal of Zoology 73(9): 1689-1698.

Sandeels (Ammodytes marinus & A. tobianus)

Conservation status: IUCN red listed as data deficient.

Fishery interactions: There is a target fishery in the North Sea, however there is a closed area for the protection of sandeels as a prey resource for seabirds and other predators near to the seabird colonies on the east coast of Scotland.

MPA Network: Mousa to Boddam MPA, North-west Orkney MPA, Turbot Bank MPA,

Wider seas: Ammodytes marinus and A. tobianus are widely distributed throughout UK and Ireland.

Protection: Sandeel fisheries measure (EU Reg 227/2013), North East UK sandeel closure.

Sandeels are small, eel-like fish which form large shoals and spend a large part of their life buried in seabed sediments. The larvae drift with currents before settling on suitable areas of coarse sand with low silt content^1,2. This requirement for a highly specific sediment type results in patchy distributions³. Otolith chemistry and biophysical models indicates that there is limited larval exchange among Scottish aggregations^4,5. Tagging studies and differences in growth rates indicate that, once they have settled on the seabed, sandeels remain within a small area⁵. This means that local aggregations may be easily depleted.

Sandeels are an important component of marine food webs providing food for many species of marine predators such as seabirds, mammals and fish. Local depletion of sandeel aggregations at a distance less than 100 km from seabird colonies may affect some species of birds, especially black-legged kittiwake⁶ and sandwich tern. Of the five species of sandeels inhabiting the North Sea, the lesser sandeel, Ammodytes marinus is the most abundant and comprises over 90% of sandeel fishery catches. 

Sandeels are an important trophic link between plankton and predatory fish, seabirds and mammals. Climate change can have a direct impact on the reproductive timing of sandeels^7,8 and their prey leading to poor recruitment of sandeels^9,10. This in turn, leads to limited prey availability for seabirds and other animals that depend on sandeels to feed their young⁹. 

Impacts 

Targeted sandeel trawl fisheries

Sandeels are targeted using small-mesh demersal trawl gear. Most of the catch consists of Ammodytes marinus, but other sandeel species are caught as well. Industrial trawl fisheries targeting sandeels may cause local depletion and do alter the age and size composition of the sandeel population. Depletion of the stocks can lead to reduced recruitment and export of larvae to other areas and reduced availability of prey for predators. 

Sandeel fisheries in EU waters of the North Sea are managed under the Common Fisheries Policy (based on advice from ICES). The management target is to maintain the biomass within each of the seven management units above the level where impaired recruitment is likely (B_escapement) whilst avoiding localised depletion. In 2000 a precautionary fishing closure was established in the north-west North Sea in order to protect sandeels as a prey resource for seabirds and other predators⁶. Fisheries in territorial waters around Shetland are subject to additional national controls which restrict access to smaller vessels and aim to conserve stocks at a level which allows adequate feeding for birds. There is no management to the West of Scotland but targeted fisheries do not currently occur in this area.

At present, Total Allowable Catch (TAC) for all management units relevant to Scottish waters of the North Sea is set at zero (with a catch of only 5000 tonnes permitted for monitoring purposes).

All towed gears (including pelagic and demersal gears)

There is little evidence regarding the sensitivity of sandeels to other demersal towed gears. The larger mesh trawl and seine nets used to catch whitefish and Nephrops do not generally catch sandeels and therefore are not expected to have any direct impact. There is some evidence that scallop dredges can kill sandeels buried in the sediment¹¹, but work from Marine Scotland Science has shown that even when equipped with a fine mesh net to sample sandeels, the efficiency is < 12%¹² and not therefore considered to pose a significant risk. The sensitivity of sandeels to hydraulic methods is likely to pose the greatest risk of all demersal towed gear used in Scotland based on the extent to which they penetrate and disturb the sediment. 

All static gears (including drift nets, gillnets, trammel nets, longlines, pots and traps) 

There is little or no interaction with static gears. Sandeels are not caught by static gears and the physical impact of these gears on the sediments that support sandeels is considered to be insignificant. 

JNCC/NatureScot advice

Targeted sandeel trawl fisheries – At present ICES advises on the TAC for sandeels in the open part of Sandeel Area 4 based on an analytical assessment for the whole area that is tuned by a research survey conducted by MSS¹³.  MPAs should be managed to ensure that local depletion does not occur and prey availability for predators is sufficient to maintain healthy populations. This implies that additional restrictions on catch or effort may be required within MPAs.  

All towed gears – measures to reduce or limit the pressures associated with hydraulic fishing gear would reduce, but not eliminate the risk to the conservation objectives. If the pressures are removed or avoided, the risk would be reduced to the lowest possible level. Other demersal towed and seine gears are not considered to have a significant impact on sandeel populations and are therefore not expected to require additional management.

All static gears - demersal static gears are not considered to have a significant impact on sandeel populations and are therefore not expected to require additional management. 

Confidence in advice

Targeted sandeel trawl fisheries – high confidence - the conclusions are supported by direct evidence. 

Hydraulic dredging – low confidence - the conclusions are supported by expert judgement from fisheries advisors.

Demersal towed and static gear – medium confidence; the conclusions are supported by direct evidence.  There is uncertainty over the possible effects of dredging.

Evidence

¹Wright, 2000; ²Holland et al 2005; ³Jensen et al. 2011; ⁴ Gibb et al., 2017; ⁵Wright et al., in press; ⁶Daunt et al., 2008; ⁷Wright et al., 2017a; ⁸Wright et al., 2017b; ⁹Eerkes-Medrano et al., 2017; ¹⁰Regnier et al., 2017¹¹Eleftheriou & Robertson 1992; ¹²MSS unpubl data ¹³ICES,2017; 

• Directly relevant peer reviewed literature
• Directly relevant grey literature
• Inference from studies on comparable habitats, gears or geographical areas.
• Expert judgement or anecdotal evidence

Reference

Daunt, F., Wanless, S., Greenstreet, S. P. R., Jensen, H., Hamer, K. C., and Harris, M. P. 2008. The impact of the sandeel fishery closure on seabird food consumption, distribution, and productivity in the northwestern North Sea. Canadian Journal of Fisheries and Aquatic Sciences, 65: 362-381.

Eerkes-Medrano, D., Fryer, R., Cook, K., and Wright, P. 2017. Are simple environmental indicators of food web dynamics reliable: exploring the kittiwake – temperature relationship. Ecological Indicators, 75: 36-47.

Eleftheriou A. and Robertson M.R. 1992 The effects of experimental scallop dredging on the fauna and Physical environment of a shallow sandy community. Netherlands Journal of Sea Research 30: 289-299.

Gibb, F. M., Régnier, T., Donald, K., and Wright, P. J. 2017. Connectivity in the early life history of sandeel inferred from otolith microchemistry. Journal of Sea Research, 119: 8-16.

Holland, G. J., Greenstreet, S. P. R., Gibb, I. M., Fraser, H. M., and Robertson, M. R. 2005. Identifying sandeel, Ammodytes marinus, and sediment habitat preferences in the marine environment. Marine Ecology Progress Series, 303: 269e282.

ICES. 2017. Report of the Benchmark on Sandeel (WKSand 2016), 31 October – 4 November 2016, Bergen, Norway. ICES CM 2016/ACOM:33. 313 pp.

Jensen, H., Rindorf, A., Wright, P. J., and Mosegaard, H. 2011. Inferring the location and scale of mixing between habitat areas of lesser sandeel through information from the fishery. ICES Journal of Marine Science 68: 43–51.

Régnier, T., Gibb, F. M., and Wright, P. J. 2017. Importance of mismatch in a winter hatching species: evidence from lesser sandeel. Marine Ecology Progress Series, 567: 185-197.

Wright, P. J., Christensen, A., Regnier, T., Rindorf, A., and van Deurs, M. in press. Integrating the scale of population processes into fisheries management, as illustrated in the sandeel, Ammodytes marinus. ICES Journal of Marine Science, fsz 013.

Wright, P.J., Orpwood, J., and Scott, B. 2017a. Impact of rising temperature on reproductive investment in a capital breeder: the lesser sandeel. Journal of Experimental Marine Biology and Ecology, 486: 52-58.

Wright, P. J., Orpwood, J. E., and Boulcott, P. 2017b. Warming delays ovarian development in capital breeder. Marine Biology, 164: 80.

Wright, P.J., Jensen, H., Tuck, I., 2000. The influence of sediment type on the distribution of the lesser sandeel, Ammodytes marinus. J. Sea Res. 44, 243–256.

Risso’s dolphin (Grampus griseus) 

Conservation status: ICUN red list as Least Concern

Fisheries interactions: Potential connectivity to fisheries for octopus and squid, which are main prey items for Rosso’s dolphin, and potential incidental catch or entanglement in fishing gear.

MPA Network: North East Lewis Nature Conservation pMPA

Wider seas: Seen worldwide but Scottish waters are of great importance for Risso’s dolphin in European waters. 

Protection: European Protected Species (EPS), UK BAP

Risso’s dolphin is a large dolphin with distinctive scars on their skin. They are slow-growing and long-lived. An estimated 86% of Europe’s Risso’s dolphins are found in UK waters with Scottish waters being a particular stronghold¹. They inhabit steep shelf-edge habitats between 400-1000m deep², due to the rich upwellings and high abundances of prey species³. Therefore, due to the geographical formation of Scotland they are most often sited inshore on the west coast. Their prey is dominated by cephalopod species, particularly the curled octopus Eledone cirrhosa and squid Todarodes sagittatus⁴. 

(NB: the main target species for squid in Scottish inshore waters is Loligo forbesi)

Impacts

All fishing vessels Disturbance to Risso’s dolphins can be caused by both vessel presence and vessel noise. Repeated or extended disturbance can result in extra expenditure of energy, masking of communication, disruption to social interactions, and a decrease in foraging activity. A reduction in feeding success could lead to a decrease in energy availability for foetal development and nursing, resulting in reduced calving rates. By altering calving rates and affecting long-term growth and survival rates of individuals, disturbance can have population level impacts.  

Reduction in prey species from important feeding areas arising from commercial fisheries has the potential to impact energy budgets for Risso’s dolphins. It is unknown if Risso’s dolphins are able to respond to a reduction in prey, e.g. through prey switching or moving to new foraging areas. However, considering Risso’s dolphins have a cephalopod-based diet, they may have limited ability to switch prey¹.

All towed gears (including pelagic and demersal gears e.g. beam trawls, otter trawl, hydraulic and scallop dredges)

Worldwide Risso’s dolphin are infrequently reported as incidental capture in trawl nets^5,6,8. In Scotland there are no records of incidental capture of Risso’s dolphin with bottom trawls or purse seine nets, however this may be an artefact of the reporting mechanism so the frequency of incidental capture in towed gears is currently unknown.

All demersal static gears (including drift nets, gillnets, trammel nets, longlines, pots and traps)

The Scottish Marine Animals Stranding Scheme (SMASS) database indicates that entanglement is a potential issue. In the last 25 years there have been three reports where entanglement in nets has been identified as the cause of death. 

Outside the UK, there is evidence to suggest that longline fisheries⁹ and drift net fisheries⁷ have high accidental capture of Risso’s dolphin.  In the Azores, Risso’s dolphins become caught on the hooks of the hand jig squid fishery while predating on the already hooked squid. This fishery has introduced Acoustic Deterrent Devices (ADDs) to try and prevent the accidental capture of Risso’s dolphins however this mitigation measure has not been proven to be successful⁸.

NatureScot Advice

All fishing vessels – The potential for disturbance could be mitigated by the same best practice as laid out for vessels in the Scottish Marine Wildlife Watching Code. This would require vigilance when travelling or fishing within the MPA, and reducing vessel speed when Risso’s dolphin are present in proximity. 

All towed gear – As there is little evidence of direct interaction between Risso’s dolphin and towed gear fisheries, no management measures are recommended at this point. However, should towed gear fisheries for cephalopod species arise in the future, the potential for incidental catch and/or reduction of prey availability should be considered. 

Management measures ensuring that fishing activity does not prevent or disrupt the availability of key prey species (e.g. cephalopod) for Risso’s dolphin should be considered.

All static gear – Exclusion of the use of drift nets and nets set on the seabed (tangle, trammel, gill) to avoid the risk of entanglement/incidental capture of Risso’s dolphin is recommended.  

The Scottish creel fishing industry recognizes entanglement as a potential issue and is working in partnership with scientists, NGO’s and government to understand the issue. The Scottish Entanglement Alliance (SEA) was formed with the support of the European Maritime Fisheries Fund to engage with the Scottish inshore creel fishing fleet to better understand the incidence of marine animal entanglements, and to develop sustainable and proportional mitigation strategies. SEA have developed, with industry, a best practice guide including methods to setting creels for reducing the risk of entanglement¹⁰.

Confidence in advice 

All fishing vessels – Medium certainty - there is published research associated with vessel disturbance for wildlife watching boats, however the relevance of this to fishing vessels needs to be considered further. 

Towed gears – Medium certainty – There is published data for other countries reporting incidental capture of Risso’s dolphin in towed gear, but very little data from Scottish waters. Incidents of capture in towed gear in the UK have been reported in grey literature but the extent of incidental captures is unknown.

Static gears - Medium certainty - Incidents of capture in nets in the UK have been reported in grey literature but the extent of incidental captures is unknown.

Evidence

¹Lancaster et al. 2014; ²Baird, 2008; ³Baumgartner, 1997; ⁴Evans, 2013; ⁵NOAA publications; ⁶Fertl & Leather wood 1997; ⁷Bearzi et al. 2008; ⁸Cruz et al. 2014; ⁹Lopes et al, 2012; ¹⁰SEA publication

• There is observed evidence for the impacts of demersal towed gears on cetaceans, not specifically Risso’s dolphin.
• Directly relevant peer reviewed literature
• Directly relevant grey literature  
• Inference from studies on comparable habitats, gears or geographical areas Expert judgement or anecdotal evidence

References

Baird, R.W. 2008. Risso's dolphin Grampus griseus. In: W.F. Perrin, B. Wursig and J.G.M. Thewissen. Eds. Encyclopaedia Of Marine Mammals, Second Edition. Academic Press, San Diego, CA, 975-976. 

Bearzi, G., Reeves, R. R.,Remonato, E., Pierantonio, N., Airoldi, S. 2008. Risso’s dolphin Grampus griseus in the Mediterranean Sea. Mammalian Biology. 76 (4): 385-400.

Baumgartner, M. 1997. The distribution of Risso’s dolphin Grampus griseus with respect to the physiography of the northern Gulf of Mexico. Marine Mammal Science, 13(4), 614-638. 

Cruz, M. J., Jordão. V. L., Pereira, J. G., Santos, R. S., Silva, M. A. 2014. Risso's dolphin depredation in the Azorean hand-jig squid fishery: assessing the impacts and evaluating effectiveness of acoustic deterrents. ICES Journal of Marine Science, 71 (9);  2608–2620 Evans, P. 2013. The Risso’s dolphin in Europe: research and conservation. In Chen, I., Hartman, K., Simmonds, M., Wittich, A. & Wright, A.J. (Eds.). Grampus griseus 200th anniversary: Risso’s dolphins in the contemporary world. Report from the European Cetacean Society Conference Workshop, Galway, Ireland. European Cetacean Society Special Publication Series No 54, 10-24. 

Fertl, D. & Leatherwood, S. 1997. Cetacean Interactions with Trawls: A Preliminary Review. Journal of Northwest Atlantic Fishery Science. 22: 219-248

Lancaster, J. (Ed.), McCallum, S., Lowe A.C., Taylor, E., Chapman A. & Pomfret, J. (2014). Development of detailed ecological guidance to support the application of the Scottish MPA selection guidelines in Scotland’s seas. Scottish Natural Heritage Commissioned Report No.491. Risso’s Dolphin – supplementary document. 

Lopez, D. M., Barcelona, S. G., Baez, J. C., de la Serna, J. M., Ortiz de Urbina, J. M. 2012. Marine mammal bycatch in Spanish Mediterranean large pelagic longline fisheries, with a focus on Risso’s dolphin (Grampus griseus). Aquatic Living Resources. 25, 321-331

NOAA. 2017. North-west Atlantic stock assessment

Scottish Entanglement Alliance (SEA)  – Best practice Guide for fishermen