Status Assessment 2021 - Gulper Shark
| Assessment of status | Distribution | Population size | Demographics, e.g. productivity | Previous OSPAR status assessment | Status | |
|---|---|---|---|---|---|---|
Region | I | NA | ||||
| II | NA | |||||
| III | NA | |||||
| IV | ←→1 | ? | ? | ● | ? | |
| V | ←→1 | ? | ? | ● | ? | |
| Assessment of key pressures | Fisheries | Threat or impact | |
|---|---|---|---|
Region | I | NA | |
| II | NA | ||
| III | NA | ||
| IV | ↓1 | ? | |
| V | ↓1 | ? | |
Explanation to table:
Distribution, Population size, Condition
Trends in status (since the assessment in the background document)
↓ decreasing trend or deterioration of the criterion assessed
↑ increasing trend or improvement in the criterion assessed
←→ no change observed in the criterion assessed
? trend unknown in the criterion assessed
Previous status assessment: If in QSR 2010 then enter regions where species occurs ( ○) and has been recognised by OSPAR to be threatened and/or declining (● ). If a more recent status assessment is available, then enter ‘poor’/’good’
Status [overall asessment]
red – poor
green – good
Blue cells ? –status unknown, insufficient information available,
NA - Not Applicable
*applied to assessments of status of the feature or of a criterion, as defined by the assessment values used in the QSR 2023 or by expert judgement.
Key pressure
↓ key pressures and human activities reducing
↑ key pressures and human activities increasing
←→ no change in key pressures and human activities
? Change in pressure and human activities uncertain
Threat or impact [overall assessment]
red – significant threat or impact;
green –no evidence of a significant threat or impact
Blue cells – insufficient information available
NA – not applicable
1 – direct data driven
2 – indirect data driven
3 – third party assessment, close-geographic match
4 – third party assessment, partial-geographic match
5 – expert judgement
(Use more than one number when mixed methods were used)
Confidence
Low
Background Information
The gulper shark was nominated for inclusion on the OSPAR List of Threatened and/or Declining Species and Habitats in 2006 and it has been included since 2009. The original evaluation against the Texel-Faial criteria listed sensitivity and decline in the OSPAR Regions where it occurs (Regions IV and V) as reasons for its listing. There is however ongoing taxonomic confusion across the genus Centrophorus, which has implications for the interpretation of all data on this Genus.
Geographical Range and Distribution
The gulper shark is thought to be distributed in the Atlantic from the waters off eastern North America to France, extending southwards to South Africa and including the Madeira and Azores archipelagos. The species possibly occurs in other areas, but the geographic range is uncertain due to misidentification with similar species in the Atlantic and other oceans (Ebert and Stehmann 2013). In the North-East Atlantic, two species of Centrophorus were previously landed under the unique scientific name of Centrophorus granulosus, including Centrophorus uyato. C. uyato is considered to be a more southerly species that also occurs in the Mediterranean while C. granulosus is known to inhabit the Iberian continental slope and more northern areas. According to White et al. (2013) C. lusitanicus Bocage & Capello, 1864 and C. niaukang Teng, 1959 are considered junior synonyms of C. granulosus.
Figure 1: Distribution of gulper shark Centrophorus granulosus (Ebert and Stehmann, 2013).
Population/Abundance
The stock structure of this species in the North-East Atlantic is unknown. Data are insufficient to evaluate either current population size or recent trends in relative abundance. Very little new information is available, as this species is rarely caught in scientific research surveys. ICES does not provide advice for this species.
Condition
The gulper shark reaches a maximum size of 176 cm total length (TL). Males mature at c.111 cm in total length; females at c.143 cm in total length (Cotton et al. 2015, Weigmann 2016). The species produces litter sizes of 1–7 pups (Cotton et al. 2015). Female age-at-maturity is estimated to be 16.5 years with a maximum age of 39 years. This results in a generation length of 27.75 years (Guallart 1998).
Threats and Impacts
A targeted longline fishery that began in the north of Portugal in 1983 included this species but this fishery stopped in 2006 (ICES 2019). Currently, the species is an occasional bycatch species in deep-water fisheries, but landings are prohibited. An exception is made for deep-water longlines targeting black scabbardfish, where a small bycatch is allowed.
Bycatch mortality, whether discarded or utilised, poses a particular challenge for the management of deep-water sharks; these species cannot be returned alive following capture in many commercial fisheries.
Fishing effort has strongly decreased in the last 15 years, given the EU management measures adopted to reduce the impact of deep-water fisheries on deep-water species, including sharks.
Measures that address key pressures from human activities or conserve the species/habitat
In the EU, a zero total allowable catch (TAC) was adopted in 2010 for a range of deep-water sharks, including the gulper shark. Since 2017, a limited TAC for deep-water sharks has been allowed for “bycatches in longline fishery targeting black scabbardfish”, with no directed fisheries permitted. Given the potential negative impact on deep-water species, gill nets, entangling nets, and trammel nets were banned for fisheries at depths >600m from 2007 onwards. In order to mitigate the potential damaging impacts of bottom trawling, fishing with bottom trawls was permitted only at depths ≤800 m after 2016. However, the gulper shark is most commonly found in the 300 to 800 metre depth range. Thus, only part of the population may be protected by these measures. In Region IV, several records assigned to this species indicate that species is known to distribute at depths >740 m (Bañon et al., 2008); in 1451–1850m strata (Diez et al., 2021).
In the Azores, bottom trawls have been prohibited in most of the EEZ since 2005 (Council Regulation (EC) No 1568/2005 of 20 September 2005; Regulation (EU) 2019/1241 of the European Parliament and of the Council of 20 June 2019; Portaria nº 114/2014, of 28 May of 2014). In the NEAFC Regulatory Area the species is designated as Category 2, which means that directed fisheries are not authorised and that bycatches should be minimised.
Conclusion (including management considerations)
Fishing pressure, identified as the only threat to the gulper shark in the last OSPAR assessment, has declined. Several fisheries regulations in the North-East Atlantic have been adopted within and beyond EU waters. However, abundance and biomass indices for this species are lacking and the data derived from discard sampling are not adequate to estimate the quantities caught. The available data are insufficient to fully evaluate the current status of the population, but the species is known to exhibit life-history traits that make the recovery process slow.
Incidental bycatch of gulper shark continues to take place in some deep-water fisheries targeting other species. Spatio-temporal management could be considered to further minimise bycatch (e.g. avoidance of some fishing grounds or times of the year where there is a spatial overlap between the target species of the fisheries and deep-water shark species) (ICES 2020). However, the information available is not adequate to frame such measures at present. Among the other possible bycatch mitigation measures for this species in deep-water fisheries is the development of gear-based technical measures for improving selectivity, such as electromagnetic exclusion devices, acoustic or light-based deterrents for example.
Knowledge Gaps
There is a worldwide concern about the misidentification of Centrophorus species and further efforts should be made to clarify the Genus and, consequently, species occurrences. For the North-East Atlantic, the knowledge on gulper shark distribution and stock structure is very deficient. Life-history and biological information are significantly lacking.
A major scientific investment is required to gain a full understanding of the spatial and temporal population dynamics that would enable estimates of sustainable exploitation levels or the development of conservation-oriented measures. This would include:
i) increased and rigorous monitoring of deep-water shark populations;
ii) development of specific studies to assess the distribution patterns of species and to estimate the spatial overlap with fisheries;
iii) evaluation of the effect on the bycatch of deep-water sharks of modifications in deep-water fishing operations (ICES 2019).
Method used
The assessment is based mainly on expert opinion with very limited data. It is derived from a mixture of OSPAR data and assessments from third parties, landings data from ICES working group reports, ICES WKSHARK6, and Red List assessments by the IUCN.
Bañon, R., C. Piñeiro, M. Casas, Biological observations on the gulper shark Centrophorus granulosus (Chondrichthyes: Centrophoridae) off the coast of Galicia (north-western Spain, eastern Atlantic), J. Mar. Biol. Assoc. U. Kingd. 88 (2008) 411–414.
Cotton, C.F., Grubbs, D.R., Dyb, J.E., Fossen, I., and Musick, J.A. 2015. Reproduction and embryonic development in two species of squaliform sharks, Centrophorus granulosus and Etmopterus princeps: Evidence of matrotrophy? Deep Sea Research Part II: Topical Studies in Oceanography 115: 41-54.
Diez, G., Arregi, L., Basterretxea, M., Cuende, E., & Oyarzabal, I. (2021). Preliminary observations on abundance and distribution of fish fauna in a canyon of the Bay of Biscay (ICES Division 8c). Journal of the Marine Biological Association of the United Kingdom, 1-10.
Ebert, D. A., and Stehmann, M. F. 2013. Sharks, batoids and chimaeras of the North Atlantic. FAO, Roma (Italia).
Guallart, J. 1998. Contribución al conocimiento de la biología y la taxonomía del tiburón batial
Centrophorus granulosus (Bloch & Schneider, 1801) (Elasmobranchii, Squalidae) en el Mar Balear (Mediterráneo occidental). Tesis doctoral, Universitat de Valencia.
ICES. 2019. Working Group on Elasmobranch Fishes (WGEF). ICES Scientific Reports. 1:25. 964 pp. http://doi.org/10.17895/ices.pub.5594
ICES. 2020. Workshop on the distribution and bycatch management options of listed deep-sea shark species (WKSHARK6).
ICES Scientific Reports, 2:76. 85 pp. http://doi.org/10.17895/ices.pub.7469.
Weigmann, S. 2016. Annotated checklist of the living sharks, batoids and chimaeras (Chondrichthyes) of the world, with a focus on biogeographical diversity. Journal of Fish Biology 88(3): 837-1037.
Sheet reference:
BDC2021/Gulper shark