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26 Other issues

26.1 Data needed to assess the bycatch of deep water sharks and possible mitigation measures to reduce bycatch

26.1.1 Background In the past, deep-sea sharks were commonly caught in European mixed deep-water fisheries operating along the Northeast Atlantic continental margin, mainly by deep- water trawlers in the ICES Subareas 4, 5, 6, 7 and 12 and by deep-water longliners in ICES Subareas 8, 9 and 10. The most important species in commercial landings were leafscale gulper shark Centrophorus squamosus, Portuguese dogfish Centroscymnus coelolepis and kitefin shark Dalatias licha. However, many other deep-water shark spe- cies were caught as bycatch, depending on the area and depth of exploitation. In general, the survival of deep-water sharks after commercial fishing operations is considered to be very low. Specimens of leafscale gulper shark and Portuguese dogfish caught by commercial fishing operations generally arrive dead onboard, highlighting that the discard survival is extremely low for the two species. The only indication of some survivorship of deep-water sharks in the Northeast Atlan- tic was observed for leafscale gulper shark caught during a scientific tagging pro- gramme. The survey used deep-water longlines which were laid at depths ranging from 900–1100 m (Rodríguez-Cabello and Sánchez, 2014). In this study, the soak time was restricted to 2–3 hours and the lines were hauled back at a slow speed (0.4–0.5 m.s– 1). It is important to note that these fishing practices are different from those used in commercial fisheries. Similarly, Brooks et al. (2015) also reported some survival of deep-water sharks, but these were also taken in scientific field studies.

26.1.2 Life history and population dynamics Life history characteristics of deep-water sharks typically include a slow growth rate, late age-at-maturity and low fecundity, indicating long generation times (Garcia et al., 2008; Graham and Daley, 2011). Their populations are considered highly vulnerable to commercial exploitation and exhibit low recovery rates when depleted (Pratt and Ca- sey, 1990; Simpfendorfer and Kyne, 2009). Due to their low biological productivity and risk of population decline after exploitation, there are worldwide concerns for their conservation (Kyne and Simpfendorfer, 2010). These concerns were the basis for the adoption, in 2005, of an EU TAC for deep-water sharks which was reduced to zero in 2010 and has remained at zero since then. Despite their overall low resilience to commercial exploitation, species present differ- ent life history traits and dynamics, and these differences should be considered in the assessment and the management of the different species. For example, some species are known to segregate by size, sex and/or maturity stage with different habitat re- quirements during their life (Moura et al., 2014). Table 26.1 summarizes some biological and ecological information of the two most commonly caught species, illustrating their likely different responses to commercial exploitation.

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Table 26.1. Summary of the main ecological and biological aspects described for the Portuguese dogfish and the leafscale gulper shark.

Leafscale gulper Portuguese dogfish shark (GUQ) (CYO) Comments

Overall Worldwide Worldwide Distribution NE Atlantic Mainly caught Commonly caught as There is bathymetric overlap distribution between 600 and 1500 deep as 2000 m, with between the two species, but m deep, with occasional records CYO reaches deeper waters. occasional records down to 2800 m [2]. CYO presents widespread down to 3300 m. For the NE and CE gene mixing across the There is apparently Atlantic there is distribution area. no genetic structure apparently no genetic in the NE Atlantic [1]. structure [4]. NE Atlantic Few records of Few records of For both species, the reasons Ontogenic neonates and small neonates and small for the scarcity of young are stages immature specimens immature specimens not clear, but it is likely that distribution (juveniles) [2]. (juveniles) [2]. they concentrate in nurseries Immature females All adult outside the areas already predominate over reproductive stages surveyed. mature females. can be found within GUQ females are less the same dispersed than males. The Mature males are more broadly geographical region latter is supported by the distributed than of the NE Atlantic [2]. observation of high levels of mature females [2]. male-mediated gene flow [1]. Pregnant females To complete the life cycle GUQ occur at specific females undertake large scale areas, such as off migrations to give birth at Madeira Archipelago specific areas. and at the norther CYO is able to complete the part of NE Atlantic [2, whole life cycle within 3]. Pregnant females different areas of the NE are spatially Atlantic. segregated from the rest of the population. ICES WGEF REPORT 2016 | 641

Reproduction Early ripe follicles are After mating, the GUQ is a continuous breeder present in the ovaries female gonad (i.e. vitellogenesis proceeds in of females in late regresses to a parallel with gestation) with a pregnancy stages. developing stage that unique reproductive season

Ovaries of early stage lasts, at least, 1 year All GUQ fully developed

pregnant females do [5]. follicles are ovulated

not present atretic Ovaries of late-stage CYO is not a continuous follicles. pregnant females breeder, after parturition Ovulation is maximal have a predominance females are likely to enter into during the second of atresia. a resting period quarter of the year Two main ovulation CYO has two ovulation [5]. periods (March-April periods in each year. High frequency of and October- Only a fraction of the mature males in a spent November) [5]. females of CYO is condition observed Significant increase of reproductively active in each from September to females in the first reproductive period October uterine stage and of females carrying the largest intra-uterine embryos in March - April and in October- November [5]. During those periods adult females in different maturity stages coexist. Growth The estimated ages of Estimates of Von The growth rates of both CYO specimens caught to Bertalanffy and GUQ are very low. the west of the British parameters were: Isles varied from 21– growth rate (k) =

70 years. 0.007; L∞ = 128.4 cm

Absence of small [7]. specimens restricted the fitting of the growth model [6].

[1] Veríssimo et al. (2012); [2] Moura et al. (2014); [3] Severino et al. (2009); [4] Veríssimo et al. (2011); [5] Figueiredo et al. (2008); [6] Clarke et al. (2002); [7] Moura et al. (2011)

26.1.3 Stock assessment In recent years, both fishery-dependent and fishery-independent data on deep-water sharks taken by Northeast Atlantic deep-water fleets have been limited and considered insufficient to monitor species abundance or biomass trends. These deficiencies are ex- acerbated by the global distribution of some species that occur in waters under many jurisdictions, and also by their specific reproductive strategies. As a consequence of all these data deficiencies, attempts to develop adequate quantitative stock assessments for deep-sea sharks have fallen short of expectations.

26.1.4 Fishery-dependent data Historical, EU fishery data available are restricted to deep-sea sharks of commercial importance, and are of limited use due to the lack of taxonomic and geographic preci- sion. European historical landing data on deep-water sharks are problematic, as for many countries (excluding Portugal) landings were often reported in generic catego-

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ries, such as “various sharks nei”. Despite the efforts to retrospectively split the histor- ical landing data into species, no objective rule was considered satisfactory (ICES, 2011). In Portuguese mainland waters (ICES Division 9.a), temporal abundance trends for fe- male Portuguese dogfish for the period 1989–2008 were modelled by a state space model with a Bayesian approach (ICES, 2011; Figueiredo et al., 2013). The model was benchmarked in 2010 (ICES, 2011) and the results showed that at the end of the time series population abundance of both recruited juveniles (70 cm < total length < 101 cm) and adults (total length > 101 cm, i.e., with length larger than the length-at-first ma- turity) were stable (Figure 26.1, upper row). It was also observed that catches of these two life history stages decreased (Figure 26.1, lower row). Both results suggested that the fishing impact on the population inhabiting Portuguese mainland waters was low (Figueiredo et al., 2013).

Figure 26.1. Portuguese dogfish – female population abundance estimates (upper row) and esti- mated catch (lower row) in numbers for non-recruited juveniles (left), recruited juveniles (middle) and adults (right), for the first scenario, and their respective 95% credible intervals (doted lines).

In the last ten years, and due to the EU restriction measures, registered catches of deep- sea sharks in the NE Atlantic have declined greatly. At the present time, although dis- carding is known to occur in existing deep-water fisheries, these have not been fully quantified. Preliminary ICES estimates are considered uncertain (ICES, 2015).

26.1.5 Fishery-independent data Some fishery-independent data are available but these are often temporally irregular. Fishery-independent data are available from Irish, Scottish and Spanish trawl surveys but none have sufficient geographic and bathymetric coverage to ensure the sampling of all demographic components of the populations. With the exception of the Scottish survey, the remaining surveys are represented by a non-continuous and short time- series (ICES, 2011). The fishery-independent data collected from the Marine Scotland Science deep-water survey in Subarea 6 are available since 1998, at depths ranging from 300–2040 m. Abun- dance indices of leafscale gulper shark and Portuguese dogfish were estimated from ICES WGEF REPORT 2016 | 643

2000 onwards, because only since then were the surveys considered standardized (Fig- ure 26.2). In the survey, the two species are not common and among the two, Portu- guese dogfish has always been caught more frequently than leafscale gulper shark.

Figure 26.2. Abundance of Portuguese dogfish, in number per hour (a) and of leafscale gulper shark in number per hour (b) for the period 2000–2013 using the Scottish deep-water trawl survey data; no surveys in 2001, 2003, and 2010 (ICES, 2015).

As these surveys take only place in a small proportion of deep-water shark stock ranges they should only be considered informative of stock abundance in Subarea 6. Further- more, the deep-water shark abundance trends derived from these surveys may not be representative of the other parts of their geographic range, and the Scottish survey abundance estimates for each species should not be extrapolated for their whole stock ranges. No fishery-independent data are available for areas further south, which pre- vents an insight on the abundance temporal trends of each species in these areas.

26.1.6 Management and ICES advice In the NE Atlantic, the stock structures of most deep-water sharks, as well as their tem- poral and spatial dynamics, are still poorly known. In the absence of more clear infor- mation on stock identity, single assessment units along the NE Atlantic have been adopted by ICES for the three most important commercial species (leafscale gulper shark, Portuguese dogfish and kitefin shark). However, it should be remarked that de- spite the assumption that leafscale gulper shark undertake large scale migrations asso- ciated with reproduction (two different birth areas have been identified), Portuguese dogfish is thought to be able to complete its life cycle in the same geographical area (Moura et al., 2014), although sampling data on neonates are limited. For leafscale gulper shark, and following a precautionary approach, ICES advised in 2015 that fishing mortality should be minimized and no targeted fisheries should be

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permitted. Similar advice was adopted for both Portuguese dogfish and kitefin shark stocks. This advice was valid for the period 2016 to 2019.

26.1.7 Description of the Portuguese longline fishery for black scabbardfish The Portuguese mainland longline fishery targeting black scabbardfish Aphanopus carbo was initiated in 1983 at fishing grounds around Sesimbra (Bordalo-Machado and Figueiredo, 2009). This fishery is organized within a specific Producers’ Organization structure (ArtesanalPesca) and operates within the context of European deep-water fisheries management. The fleet targeting black scabbardfish off the Portuguese conti- nental slope is currently comprised of fewer vessels than at the beginning of the fishery (Bordalo-Machado and Figueiredo, 2009). In the 1980s, the fishing grounds for black scabbardfish fishery were located in Sesimbra but, in 2000, the introduction of technical improvements in some vessels al- lowed an expansion of this fishery to grounds located northwards and farther away from the coast. The total number of hooks increased; from around 3 600–4 000 hooks per fishing gear at the beginning of the fishery and 4 000–10 000 in 2008, remaining constant afterwards. Furthermore, as at the beginning of the fishery, the fidelity of each vessel to a fishing ground is maintained, i.e., each vessels fishes at one or fewer loca- tions for many years (Bordalo-Machado and Figueiredo, 2009).

26.1.8 Data needed to assess the bycatch of deep-water sharks by fishery and possible mitigation measures to reduce bycatch WGEF does not have sufficient information of good quality to propose bycatch levels sustainable to the stocks of deep-water sharks either in the Portuguese longline fishery and in any other deep-water fishery. Major scientific investment would be required to gain a full understanding of the spa- tial and temporal population dynamics of deep-water sharks and to enable estimates of sustainable exploitation levels. In the constrained financial environment, the fishery-independent surveys for deep- water species in NE Atlantic proposed by WGNEACS were not initiated. In 2009–2010 an internationally coordinated longline survey was proposed by AZTI, IEO, IPMA and IFREMER in the WGNEACS, and this was presented to the November 2013 STECF plenary meeting. STECF (2013) concluded that a “long-line survey would be an appropriate method for monitoring the status of some of the species present in areas spanning the 300 to 2100 m isobaths in ICES Subareas 8 and 9” and recommended: (i) the inclusion of measures to minimise the mortality of deep-water sharks and, (ii) an assessment of the extent to which any mortality of deep-water sharks resulting from this survey will affect their rates of recovery. Several strategies should be adopted to monitor species abundance and evaluate fish- ing impact on their populations by the different deep-water fisheries. These include the adoption of management measures and funding to assure the increase of scientific efforts towards the:  increase of close monitoring of deep-water shark populations;  development of specific studies to assess the distribution patterns of species and estimate the spatial overlap with fisheries;  evaluation of the effect on the by catch of deep-water sharks of modifications in deep-water fishing operations; ICES WGEF REPORT 2016 | 645

 evaluation of options for spatial management measures to reduce bycatch.

26.1.8.1 Closer monitoring of deep-water shark populations Given the deterioration of fishery-dependent data collection since the implementation of EU measures (TAC = 0 t), that led to the increase of unreported discards, the evalu- ation of stock status through commercial CPUE has not been possible. The actual stock status of all species is thus unknown. A dedicated data collection program is needed to increase the number and quality of fishing data. The internationally coordinated longline survey in ICES Subareas 8 and 9 that was pro- posed by AZTI, IEO, IPMA and IFREMER in the scope of WGNEACS, focused mainly on collecting data on black scabbardfish and deep-water sharks and presented to the STECF in 2013. Longlines were preferred over trawl nets, given the existence of several non-trawlable grounds in ICES Subareas 8 and 9. STECF noted that “additional data on trends in the distribution and abundance of black scabbardfish and deep-water sharks in 8 and 9, such as those that would be collected during a well-designed long-line survey, could make a significant contribution to assessing the status of these stocks. However, a time series of at least 5 surveys (these could be at intervals >1 year) will be required in order for the results to be useful for stock assessment purposes”. Despite the recognition of the importance of such a survey, the lack of funding prevented the execution of this coordinated plan. Isolated and short-term initiatives have been carried by Portugal and the Basque Country, but conclusions cannot be used to inform on abundance or biomass of deep-water sharks.

26.1.8.2 Species distribution patterns and spatial overlap with deep-water fisheries Mitigation measures to reduce the bycatch of deep-water sharks in commercial fisher- ies require a better knowledge on species dynamics, particularly on species distribu- tion in space (geographic area and depth) and time, including the evaluation of possible segregation between sexes, size or maturity stages. With this knowledge new management measures may be proposed to include, for example, identifying potential closed areas where there may be a high abundance of sharks or a high abundance of particularly vulnerable life history stages (e.g. new-borns or pregnant females). Efforts have been developed to evaluate the level of spatial overlap between the target species (black scabbardfish) and the two main bycatch species (Portuguese dogfish and leafscale gulper shark) in the Portuguese mainland deep-water longline fishery. In 2012, the EU financed the project “Reduction of deep-sea shark bycatches in the Portuguese longline black scabbard fishery” (Ref. MARE C3/IG/re ARES (2011) 1021013). The spatial overlap between black scabbardfish and the two deep-water shark species could not be fully assessed, as sampling levels and spatial coverage were small. Sampling was restricted to the exploited areas of the deep-water longline fisheries targeting black scabbardfish, which, in mainland Portugal, are site specific. Since no other information was available for adjacent areas of those fishing grounds, the assessment of the spatial overlap was not possible. In 2014 and 2015 IPMA, under an EU co-financed project (CERTIFICA), held a short duration pilot survey onboard Portuguese deep-water longliners involved in the black scabbardfish fishery. The survey took place onboard five commercial longliners. Each vessel performed two fishing hauls: one located at the fishing grounds usually ex- ploited by the vessel and the other located in areas deeper but adjacent to the usually exploited fishing grounds. For the two deep-water shark species, results indicated that they spatially overlapped with black scabbardfish. However, the proportions of deep-

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water sharks were consistently higher in fishing hauls performed in deeper areas ad- jacent to the black scabbardfish fishing grounds (Table 26.2). These observations are not in agreement with a uniform spatial distribution of the deep-water sharks, as zones with consistently higher abundance of deep-water sharks were found. In the case of leafscale gulper shark, despite it consistently appearing in the fishing grounds of black scabbardfish, the species was more frequent in deeper areas than the black scabbard- fish fishing grounds. Portuguese dogfish had a patchier distribution, showing places where its occurrence had minor overlap with black scabbardfish and areas of much higher abundance. ICES WGEF REPORT 2016 | 647

Table 26.2. Mean depth of each fishing haul from the pilot survey and respective deep-water shark proportion values. The proportions were estimated as the catch value, in weight, of Portuguese dogfish in relation to the total catch of black scabbardfish and Portuguese dogfish and as, the catch value of leafscale gulper shark in relation to the total catch of black scabbardfish and of the leaf- scale gulper shark (BSF_FG, black scabbardfish fishing ground; BSF_nFG, no black scabbardfish fishing ground; PCYO, proportion of Portuguese dogfish; PGUQ, proportion of leafscale gulper shark).

BSF_FG BSF_NFG

BLACK SCABBARDFISH FISHING GROUND NO BLACK SCABBARDFISH FISHING GROUND VESSEL Depth PCYO PGUQ Depth (m) PCYO PGUQ CODE (m)

Vessel 1 1170 0 0.026 1463 0.884 0.881 Vessel 2 1357 0 0.148 1461 0.893 0.334 Vessel 3 1180 0.224 0.074 1376 0.720 0.267 Vessel 4 1198 0.122 0.112 1382 0.820 0.734 Vessel 5 1189 0.058 0.110 1445 0.279 0.044

During the same project, the spatial overlap between each deep-water shark species and black scabbardfish was evaluated using fishery-dependent data (vessel monitor- ing systems, logbooks and official daily landings) for the period between 2002 and 2006 using geostatistical methods (Veiga et al., 2013). It was concluded that in fishing grounds where black scabbardfish was more abundant, the relative occurrence of leaf- scale gulper shark is reduced. In the case of Portuguese dogfish, areas where the spe- cies is highly concentrated, within which black scabbardfish was almost absent, were observed (Figure 26.3; ICES, 2015; Figueiredo et al., in prep.). The proportion of Portu- guese dogfish in relation to the total catch of the sum of black scabbardfish and Portu- guese dogfish, was higher at Sesimbra and Centre regions.

Figure 26.3. Spatial distribution of the proportion of Portuguese dogfish around Sesimbra (2002– 2006): [0; 0.2[ (blue) [0.2; 0.7[ (green) [0.7; 1] (red).

More data on species distribution and their overlap with black scabbardfish are re- quired to have a more robust estimation of the overlap level. In fact, despite being known that both species of deep-water sharks segregate by sex, size and maturity

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stage, the areas of concentration or preferential distribution of each of these groups are still insufficiently documented.

26.1.8.3 Modification of the fishing operations Although gear modification has been advanced as a possible way to mitigate bycatch of deep-water sharks, the few experiences already performed were not successful. Whilst gear modifications (e.g. hook size and type; material used for leaders, bait type) may influence catch rates of particular species in some longline fisheries, there are in- sufficient data to indicate whether such measures would be appropriate for mitigating shark bycatch in deep-water longline fisheries. In 2012, the EU financed the project “Reduction of deep-sea shark bycatches in the Portu- guese longline black scabbard fishery” (Ref. MARE C3/IG/re ARES (2011) 1021013) that aimed, between others, to test gear modifications to minimize the deep-sea sharks by- catch (ICES, 2014). In 2015 AZTI conducted a pilot longline survey in ICES Division 8c onboard a modified commercial fishing vessel. The proposal of the survey received a letter of support by the Southwestern RAC (Regional Advisory Council) and it was funded by the Direc- torate of Fisheries and Aquaculture of the Basque Country Government. The main ob- jectives of the survey were to test the suitability of the commercial longline fishing gear (for deep-water sharks) for providing biodiversity and biomass estimates, and to test the viability of coupling depth, salinity and temperature sensors to the fishing gear (Diez et al., 2015 WD). The fishing gear used in the survey was a modified version of the deep-water longline used by commercial vessels. The gear included two equal horizontal line sections of 1750 m +1750 m, each with 150 hooks (300 in total), the horizontal line stones were removed and replaced by two “floating” sections of 75 + 75 hooks, which increased the buoyancy of the fishing gear (Figure 26.4). That modification resulted on an improve- ment of the fishing gear efficiency on catching species that feed above the bottom. Results showed that the diversity of deep-water species, including sharks, was higher when the gear had hooks placed near the bottom. To reduce the fishing mortality over these species, the effective fishing time was approximately 2 hours, that is much lower than used in commercial fishing operations. This lower soak time was pointed as one of the reasons for the low catches of species, even of teleosts (only 7.6% of hooks caught fish). The use of floating sections in the fishing gear led to a reduction of deep-water sharks catches (Diez et al., 2016 WD); the percentage of sharks caught in the floating sections was lower (<17%) than in the sections placed over the bottom. In contrast to deep-water sharks, teleosts were caught in a greater proportion in the floating sections (Table 26.3). The AZTI survey also contributed for a better perception of scientists on the design of the fishing gear, on fishing operations with longline, such as the use of sensors for monitoring the gear deployment, on sampling strategies and on the selection of meth- ods for biomass estimation. ICES WGEF REPORT 2016 | 649

Figure 26.4. Scheme of the long-line fishing gear used in the AZTI pilot survey.

Table 26.3. Catchability (in percentage) per group of species depending on the section in the fishing gear (bottom or floating)

SECTION SHARKS CHIMAERA TELEOSTS

BOTTOM 83% 100% 63% FLOATING 17% 0% 37%

Recently, AZTI conducted a selectivity study on the Spanish trammel net, the “rasco” fishery that targets monkfish in the Bay of Biscay. The “rasco” fleet uses sunken gillnets with 280 mm mesh size and a low hanging ratio. Body dimensions of the main deep- water sharks caught in this fishery, e.g. max width of the head and body, diameter of the head, were analysed. Areas of the fishing gear with high bycatch of deep-water shark were identified; being sharks mainly caught at middle of the net. Small-bodied sharks like Etmopterus spp., and juveniles of large species were not commonly caught by the gear. To reduce the bycatch of deep-water sharks more knowledge on “rasco” selectivity is still required, as well as, the introduction of gear modifications that pre- vent the net from folding at the bottom and therefore be less effective on catching spe- cies (deep-water sharks) with head and body dimensions larger than the mesh size of the fishing gear (Mugerza et al., 2014)

26.1.9 Recommendations The zero TAC adopted for deep-water sharks by the EU since 2009, together with the insufficient spatial coverage of scientific deep-water surveys contribute to an ongoing shortage of data to inform on the current stock status and on the biomass trends of the two main species caught: leafscale gulper shark and Portuguese dogfish. In the Portuguese deep-water longline fishery targeting black scabbardfish, the knowledge already available together with the site fidelity of the fishing grounds and the inevitability of unwanted bycatch of deep-water sharks, in a proportion in weight at about 15%, lead WGEF to recommend:  ‘freezing’ the actual fishing grounds used by the deep-water longline fleet targeting the black scabbardfish in ICES Division 9.a;  the design of a robust plan for monitoring the deep-water shark bycatch of the whole fleet targeting black scabbardfish;  the assignment of a special fishing licence to vessels belonging to the deep- water longline fleet that targets the black scabbardfish in ICES Division 9.a,

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carrying an obligation to provide detailed data for evaluation of deep-water sharks status in ICES Division 9.a;  the obligation to conduct a science fishery survey every two years in fixed stations adjacent to black scabardfish fishing grounds to monitor the biomass and abundance of deep-water shark in those areas. WGEF considers that the above recommendations would help address the current data limitations and provide representative information to guarantee the close monitoring of deep-water sharks in ICES Division 9.a, as well as informing on appropriate mitiga- tion measures for deep-water shark bycatch if abundance or biomass indicators sug- gested deviation from Good Environmental Status.

26.2 Discard survival WGEF note that the discarding of skates (Rajidae) occurs in a variety of fisheries across the ICES area. This discarding may include both regulatory discarding, when quota is limited, as well as the discarding of smaller are less marketable individuals. ICES WGEF consider that discarding is variable but has not been quantified, and there may be some discard survival; therefore, WGEF cannot quantify the corresponding dead catch. To date there have been only limited scientific studies of the discard survival of skates in European fisheries, and data on the immediate, short-term survival and longer-term discard survival of these species are lacking for most fisheries. To inform discussions on the future EU landing obligation and to improve the quanti- fication of dead discards, WGEF recommend the need to implement scientific studies to better assess and quantify the discard survival of the main commercial skates caught by the trawl fleets, especially otter trawlers operating in the Bay of Biscay and Iberian waters, beam trawl fleets operating in northern Europe and for gill- and trammel net fisheries used by the inshore polyvalent fleet.

26.3 Proposal for an ICES Workshop on Elasmobranch Discards (WKSHARKS2) WGEF recommend that a dedicated workshop be convened to address elasmobranch discarding issues. This will help ICES make some progress from landings to catch ad- vice for these stocks, as well as providing a suitable forum for more holistic analyses of relevant data that will provide important information for the development of other approaches for assessing elasmobranch stocks. WGEF recommend that this workshop (WKSHARKS2) be co-chaired by Pascal Lo- rance (France) and Jan Jaap Poos (Netherlands) and be held at IFREMER, Nantes from 20–24 February 2017. The suggested ToRs for this workshop are: a ) Evaluate current sampling programmes for discards to evaluate for which stocks there are sufficient data to allow for estimation of total discards, and to determine the optimal methods for raising discards data for stocks of in- terest; b ) Evaluate the suitability of existing national programmes for the estimation of discard rates and quantities for case-study elasmobranchs, considering their often seasonal and sometimes localised nature. Preliminary studies will focus on specified case-study species and metiers, representing species with contrasting levels and qualities of data, including: (i) porbeagle shark ICES WGEF REPORT 2016 | 651

Lamna nasus (e.g. in net and trawl fisheries operating in the Celtic Sea), (ii) tope Galeorhinus galeus; (iii) spurdog Squalus acanthias in net and trawl fish- eries; (iv) smooth-hounds Mustelus spp.; (v) skates, representing data-rich (e.g. thornback ray, cuckoo ray) and data-limited stocks (e.g. blonde ray) and (vi) deep-water squaliform sharks; c ) Examine the discard-retention patterns of elasmobranch species captured by (i) beam trawl, (ii) bottom otter trawl, (iii) gillnets and (iv) longlines; d ) Examine the suitability of existing national programmes to inform on the bycatch of rare elasmobranch species (e.g. basking shark and angel shark), and identify which areas, seasons and gears for which more informative data on discarding of rare species could be collected; e ) Review available studies to identify where there are existing data on the at- vessel mortality and post-release mortality of elasmobranch species by gear type and identify important data gaps Participants should ensure that raw data from national observer programmes are brought to the meeting to facilitate analyses. This workshop is relevant to: WGEF, WKMEDS, INTERCATCH, WGBYC and WGCATCH.

26.4 References

Bordalo-Machado, P., and Figueiredo, I. (2009). The fishery for black scabbardfish (Aphanopus carbo Lowe, 1839) in the Portuguese continental slope. Reviews in Fish Biology and Fisheries, 19, 49–67.

Brooks, E. J., Brooks, A. M., Williams, S., Jordan, L. K., Abercrombie, D., Chapman, D. D., Howey-Jordan, L. A. & Grubbs, R. D. (2015). First description of deep-water elasmobranch assemblages in the Exuma Sound, The Bahamas. Deep Sea Research Part II: Topical Studies in Oceanography 115, 81–91.

Clarke, M.W., Connolly, P.L., and Bracken, J.J. (2002). Age estimation of the exploited shark Cen- trophorus squamosus from the continental slopes of the Rockall Trough and Porcupine Bank. Journal of Fish Biology, 60, 501–514.

Diez. G., Arregi, L., Basterretxea, M., Onandia I., and Mugerza. 2016. Longline deep-water pilot survey for the estimated abundance of sharks and teleost species in the Bay of Biscay (ICES Division VIIIc). Working Document for the ICES Working Group on the Biology and As- sessment of Deep-Sea Fisheries Resources, Copenhagen (Denmark), 20–27 April 2016, 9 pp.

Figueiredo, I., Moura, T., Neves, A., and Gordo, L.S. (2008). Reproductive strategy of leafscale gulper shark, Centrophorus squamosus, and Portuguese Dogfish, Centroscymnus coelolepis, on the Portuguese continental slope. Journal of Fish Biology, 73, 206–225.

Figueiredo, I., Natário, I., Moura, T., and Carvalho, M. L. (2013). Modelling the dynamics of the deepwater shark Centroscymnus coelolepis off mainland Portugal. Aquatic Living Resources, 26, 355–364.

Garcia, V. B., Lucifora, L. O., and Myers, R. A. (2008). The importance of habitat and life history to extinction risk in sharks, skates, rays and chimaeras. Proceedings of the Royal Society of London. B – Biological Sciences, 275, 83–89.

Graham, K. J., and Daley, R. K. (2011). Distribution, reproduction and population structure of three gulper sharks (Centrophorus, Centrophoridae) in south-east Australian waters. Marine and Freshwater Research, 62, 583–595.

ICES (2011). Report of the Workshop on splitting of deep-water shark historical catch data 2011 (WKSHARK). 17th June 2011, Copenhagen, Denmark. ICES 2010/2/ACOM36 25pp.

ICES (2014) Report of the Working Group on Elasmobranch Fishes (WGEF), 17–26 June 2014, Lisbon, Portugal. ICES CM 2014/ACOM:19. 887 pp.

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ICES (2015). Report of the Working Group on Elasmobranch Fishes (WGEF), 17–23 June 2015, Lisbon, Portugal. ICES CM 2015/ACOM:19. 711 pp.

Kyne, P. M., and Simpfendorfer, C. A. (2010). Deepwater chondrichthyans. Sharks and their rel- atives. II. Biodiversity, adaptative physiology, and conservation. CRC Press, New York, 37– 114.

Moura T. (2011). Reproductive strategy and population structure of Centroscymnus coelolepis (Chondrichthyes: Somniosidae): a scientific support for management advice. PhD thesis. Universidade de Lisboa, Faculdade de Ciências.

Moura, T., Jones, E., Clarke, M.W., Cotton, C.F., Crozier, P., Daley, R.K., Diez, G., Dobby, H., Dyb, J.E., Fossen, I., Irvine, S.B., Jakobsdottir, K., López-Abellán, L.J., Lorance, P., Pascual- Alayón, P., Severino, R.B., and Figueiredo, I., (2014). Large- scale distribution of three deep- water squaloid sharks: integrating data on sex, maturity and environment. Fisheries Research, 157, 47–61.

Mugerza, E., Diez, G., Canive, I., Aboitiz X. & Santurtun M. (2014). Estudio de poblaciones de tiburones de profundidad como capturas accidentales de la pesquería centinela de rascos. AZTI Tecnalia Marine Research Division.

Pratt, H. L., and Casey, J. G. (1990). Shark reproductive strategies as a limiting factor in directed fisheries, with a review of Holden’s method of estimating growth parameters. NOAA Tech. Rep. NMFS, 90, 97–109.

Rodríguez-Cabello, C., and Sánchez, F. (2014). Is Centrophorus squamosus a highly migratory deep-water shark? Deep Sea Research Part I: Oceanographic Research Papers, 92, 1–10.

Scientific, Technical and Economic Committee for Fisheries, STECF. (2013). 44th Plenary Meeting Report (PLEN-13-03). Publications Office of the European Union, Luxembourg, EUR 26332 EN, JRC 86096, 124 pp.

Severino, R. B., Afonso-Dias, I., Delgado, J., and Afonso-Dias, M. (2009). Aspects of the biology of the leaf-scale gulper shark Centrophorus squamosus (Bonnaterre, 1788) off Madeira archi- pelago. ARQUIPÉLAGO-Life and Marine Sciences, 57–61.

Simpfendorfer, C. A., and Kyne, P. M. (2009). Limited potential to recover from overfishing raises concerns for deep-sea sharks, rays and chimaeras. Environmental Conservation, 36, 97–103.

Veiga, N., Moura, T., and Figueiredo, I. (2013). Spatial overlap between the leafscale gulper shark and the black scabbardfish off Portugal. Aquatic Living Resources, 26: 343–353.

Veríssimo, A., McDowell, J.R., and Graves, J.E. (2011). Population structure of a deep-water squaloid shark, the Portuguese dogfish (Centroscymnus coelolepis). ICES Journal of Marine Sci- ence, 68: 555–563.

Veríssimo, A., McDowell, J.R., and Graves, J.E. (2012). Genetic population structure and connec- tivity in a commercially exploited and wide-ranging deepwater shark, the leafscale gulper (Centrophorus squamosus). Marine and Freshwater Research, 63: 505–512.