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New data on the occurrence of the critically endangered common angelshark, Squatina squatina, in the Croatian Adriatic Sea

December 2017
Natura Croatica 26(2):313-320

DOI:10.20302/NC.2017.26.23

Authors:

Croatian Natural History Museum

Two out of three critically endangered species of angelsharks (genus Squatina (Dumeril, 1806)) inhabiting the Mediterranean have been recorded in the Adriatic Sea, namely smoothback angelshark S. oculata Bonaparte, 1840 and common angelshark S. squatina (Linnaeus, 1758). While S. oculata has been extirpated from the Adriatic Sea due to overfishing, the presence of S. squatina remained questionable and some authors propose the species is regionally extinct since the 1980s. We present new data on the occurrence of S. squatina in the Croatian Adriatic Sea based upon inspection of collections from natural history museums and literature sources as well as three new records resulting from bycatch in commercial bottom trawls in 2016 and 2017. A low overall number of records and the complete absence of the species in scientific trawl surveys conducted since 1958, indicate its low abundance and question the effectiveness of scientific surveying in detecting rare species. Our analysis showed that this formerly abundant species is still present in the Adriatic Sea, emphasizing the importance of implementing novel approaches, such as citizen-science programmes, in studying its current distribution. Although the legal framework for angelshark conservation already exists, poor implementation and lack of any species-specific conservation measures will most probably result in further population declines and extinction of S. squatina from the Adriatic Sea.

Approximate landing locations (numbers correspond to Tab. 1) and presumed distribution (Jardas et al., 2008) of common angelshark S. squatina in Croatian Adriatic Sea.

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Nat. Croat. Vol. 26(2), 2017 313

NAT. CROAT. VOL. 26 No 2 313-320 ZAGREB DECEMBER 31, 2017

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1, 2 3,4

1

2

3



Juraj Dobrila

    -

Squatina squatina



Squatina  in

 tS.

oculataS. squatina S. oculata

S. squatina



S. squatina

















S. squatina



   Squatina

squatina



Squatina S. oculataS. squatina 

S. oculataS. squatina



S. squatina

 



 





znanosti za građane

314 Holcer, D. & Lazar, B.: New data on the occurrence of the critically endangered common angelshark...









SquatinaChondrichthyes: 



 et al.



 et al. et al.

quatina



S. squatina et al.S. californica 

 et al.



 et al.

S. aculeataS. oculata

S. squatina



 et al. et al. S. aculeata 



S. oculataS. squatina



 et al. et al.

 et al. et al.S. oculata

 et al.

S. squatina





S. squatina

 et al.



 et al. et al. et al.

 et al.

 et al.S. squatina 

 et al.

 et al.S. squatina



 et al. et al.



 et al.

 et al.

 et al.

S.

squatina



















Nat. Croat. Vol. 26(2), 2017 315















S. squatina et al.



S. squatina





S. squatina









S. squatina

 S. oculataRhina oculataRhina

Squatina

S. oculata



 et al.S. squatina

316 Holcer, D. & Lazar, B.: New data on the occurrence of the critically endangered common angelshark...

Squatina

  Date   

 

    



1S. squatina       

2S. squatina       

3S. squatina*       

S. squatina        

S. squatina       

 

 

S. squatina       

 

 

S. squatina 

      Rhina squatina 



S. squatina       Rhina squatina 



S. squatina       Rhina squatina 



10 S. squatina        Rhina squatina 



11 S. squatina    2321 

12 S. squatina      

13 S. squatina       

 S. squatina        30

 S. squatina        

 S. squatina        

 S. squatina        

 S. squatina      2013

 S. aculeata*        Squatina mbriata 

20 S. oculata*      Rhina oculata 







Nat. Croat. Vol. 26(2), 2017 317



S. fimbriata , 

S. aculeata  et al.



S. aculeata,







 et al.



 et al.





 et al.

 et al.

S. squatina et al.





 et al.





 et al.

S. squatina



















 et al.







 S. squatina,



318 Holcer, D. & Lazar, B.: New data on the occurrence of the critically endangered common angelshark...













S. squatinaS. oculata

S. aculeata



















S. squatina



squatina







 et al.



et al.



 et al.S. squatina

















Received December 10, 2017









12

3





 16



50







Nat. Croat. Vol. 26(2), 2017 319



. 115





















3







 Squatina oculata           



Squatina squa-

tina 







3



Squatina squatina

772









58









20





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



   

53

Squatina squatina

24

: 

16,



1734







 Squatina squatina

320 Holcer, D. & Lazar, B.: New data on the occurrence of the critically endangered common angelshark...

Squatina

aculeata

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et al

Squatina aculeata 

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7

Updated Checklist of Chondrichthyan Species in Croatia (Central Mediterranean Sea)

Article

Full-text available

Jul 2023

Simple Summary Relatively little is known about cartilaginous fishes (sharks, rays, skates, and chimaeras) in the Adriatic Sea. Still, many tons of these endangered animals are caught every year and not many protective measures are in place. How this exploitation affects their populations today, in the past and in the future is unknown. Our study outlines a list of all species known to occur in Croatia based on historical as well as new data. This updated information establishes a baseline for further research and can help policymakers make informed decisions on conservation measures for these fishes. Abstract Almost half of all chondrichthyan species in the Mediterranean Sea are threatened with extinction, according to the IUCN Red List. Due to a substantial lack of access to data on chondrichthyan catches in the Mediterranean Sea, especially of threatened species, the implementation of conservation measures is extremely insufficient. This also concerns the Adriatic Sea. Here we present a detailed and up-to-date assessment of the species occurring in Croatian waters, as the last checklist of chondrichthyans in Croatian waters was conducted in 2009. Occurrence records from historical data, literature and citizen science information have been compiled in order to present a comprehensive list of species occurrences. We found 54 chondrichthyan species between 1822 and 2022, consisting of a single chimaera, 23 rays and skates, and 30 shark species. Here, four additional species are listed but are considered doubtful. Five species are reported here for the first time for Croatian waters that were not listed in the survey from 2009. Nearly one-third of the species reported here are critically endangered in the entire Mediterranean Sea, based on the IUCN Red List. Additionally, we revisited the Croatian records of the sandtiger shark Carcharias taurus Rafinesque, 1810 and discussed its potential confusion with the smalltooth sandtiger shark Odontaspis ferox (Risso, 1810). Our results thus provide novel insights into the historical and current distribution patterns of chondrichthyan fishes in the Croatian Sea and provide a basis for further research as well as conservation measures.

Extinct but not entirely: A new occurrence of the critically endangered Squatina squatina (Linnaeus, 1758) stresses the urgency of its conservation in the Adriatic sea

Article

Apr 2023
ESTUAR COAST SHELF S

The common angel shark (Squatina squatina), a critically endangered species inhabiting the Mediterranean Sea, has been extirpated and considered locally extinct in the Adriatic Sea due to historical intense targeted fisheries. Sighting and catches of the species are indeed currently occasional in the area. Here, we present a new record of a juvenile of common angel shark in the central Adriatic Sea and we review 135 additional specimens documented in the area since 2000s, after 40-years of no sightings. According to previous findings, our evidence suggest that the central Adriatic Sea may be a relevant habitat for early life stages of common angel shark. Due to the serious threatened status of the species, we stress the importance of urgent conservation actions needed in the Adriatic Sea.

Identifying Potential Critical Angel Shark Areas in Türkiye, Eastern Mediterranean Based on New Records of Squatina spp. Identified through Fisher Engagement

Article

Full-text available

Jul 2024

This study presents new records of three Critically Endangered angel shark species (Family: Squatinidae) occurring in the Eastern Mediterranean—Smoothback Angelshark S. oculata Bonaye, 1840, Sawback Angelshark S. aculeata Cuvier, 1829, and Angelshark S. squatina (Linnaeus, 1758). The supporting data serves to highlight three potential Critical Angel Shark Areas (CASAs) in Türkiye: Fethiye Bay, Çanakkale Strait (i.e., Dardanelles), and Antalya Bay. These data also demonstrate that female S. oculata may mature at a smaller size than prior published estimates of length at first maturity. This new dataset provides details of 23 S. squatina specimens, 52 S. oculata specimens, and 5 S. aculeata specimens, totalling 80 recent angel shark specimens found in Turkish waters mostly sent to us from small-scale fishers who had incidentally caught angel sharks. Also presented are four capture-induced parturition events in Turkish waters onboard fishing vessels, thus providing details on internal yolk sacs, reproductive habitats, and indications of spawning season. Our dataset presented here spans from 2018 to 2023 and suggests that mature adults of S. squatina and S. oculata still occur in Turkish waters, in Fethiye Bay and Çanakkale, respectively. Due to elevated chances of fishers encountering Critically Endangered angel sharks in Türkiye, we suggest that fishers are trained in handling and safe-release methods, to ensure reduced incidents of capture-induced parturition, and improved post-release survival. This study demonstrates that bottom set nets set by small-scale fishers pose less risk to mortality for angel sharks as they are almost always encountered alive after a usual 12 h soak time, suggesting that bottom trawling in critical habitats should be better regulated (or phased out) to help improve national angel shark conservation initiatives.

Comment on Balàka et al. Updated Checklist of Chondrichthyan Species in Croatia (Central Mediterranean Sea). Biology 2023, 12, 952

Article

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Feb 2024

The authors write that the last checklist for Croatia was carried out in 2009 and that 52 chondrichthyan species were reported in Croatian waters [...]

Reply to Soldo, A.; Lipej, L. Comment on “Balàka et al. Updated Checklist of Chondrichthyan Species in Croatia (Central Mediterranean Sea). Biology 2023, 12, 952”

Article

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Feb 2024

Reply to Soldo, A.; Lipej, L. Comment on “Balàka et al. Updated Checklist of Chondrichthyan Species in Croatia (Central Mediterranean Sea). Biology 2023, 12, 952”

Article

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Feb 2024

Using Local Ecological Knowledge of Fishers to Identify the Presence and Habitats of Angelsharks in Albanian Waters

Article

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Aug 2023

The Mediterranean Sea is a hotspot for shark and ray extinctions and is home to the following three angelshark species: sawback angelshark Squatina aculeata, smoothback angelshark Squatina oculata, and common angelshark Squatina squatina. We conducted a questionnaire-based survey in four coastal regions of Albania, Shëngjin (Lezhë), Vlorë, Himarë (Sarandë) and Durrës, with the aim of collecting historical and current data on angelshark catches in the Albanian seas (Adriatic and Ionian Seas). Although the occurrence of common angelshark was reported by Croatian fishermen in the Adriatic Sea, we included the other two species in our study. The number of observations was minimal, although this is the first study of angelshark species sightings in Albania. It will establish a baseline study that will allow further work on the conservation of these regionally extinct and highly endangered species.

Overview of the Angel Sharks in the Mediterranean Sea

Chapter

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Jan 2025

Three species of angel shark are present in the Mediterranean Sea with overlapping ranges: The Sawback angelshark Squatina aculeata, the Smoothback angelshark Squatina oculata and the angelshark Squatina squatina. All three are classified as critically endangered according to the IUCN due to past population reductions and are listed under the binding recommendation GFCM/42/2018/2 (amending GFCM/36/2012/3). This recommendation prohibits the retention and sale of the three species. A recent survey confirms the dramatic decline of their populations in all of the Mediterranean Sea. The compilation of bibliographic and unpublished data show that only 280 angelsharks were sighted (all species confused) during the last 30 years. The eastern (GSA 22) and the central Mediterranean Sea (GSA 12, 13, 14 and 15) represent an important area for Squatinidae species. All life stages were reported; however, maturing specimens dominate the sighting individuals. Bottom trawl and trammel nets were the gear most affected by the Squatinidae population due to their benthic and shallow habitat range. Considering the status of the species and their life history parameters, Squatinidae are highly vulnerable to fisheries. Therefore, immediate measures should be taken to conserve these species. These measures must be prioritized on: fisheries, habitats and legislation.

Local Ecological Knowledge and Fishery Data Provides Important Information on the Distribution and Seasonal Dynamic of Critically Endangered Angel Sharks in Corsica (Mediterranean Sea, France)

Preprint

Jan 2024

An inventory of Bramble sharks Echinorhinus brucus (Bonnaterre, 1788) (Elasmobranchii, Echinorhinidae) in natural history collections worldwide for conservation status assessment

Article

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Nov 2023
ZOOSYSTEMA

Many elasmobranch populations were already depleted well before fishery surveys had even started, which means historical investigations are needed to reveal their ignored declines. This is probably the case for the Bramble shark Echinorhinus brucus (Bonnaterre, 1788) whose populations in Europe are suspected of having decreased significantly. In order to document this data deficiency, an inventory of Bramble shark material that had been preserved in natural history collections, was conducted in the period 2014-2022. A total of 128 collections were contacted around the world, and additional sources of information were traced and consulted (e.g. collection labels, museum registers, digital databases, index cards, pictures, manuscripts and publications). This resulted in a list of 234 entries, subsequently assigned to 169 individual Bramble sharks. These exhibits are, or had been deposited in 80 different collections, spread over 22 countries, whereas the other 48 collections yielded no results. At least 40 entries are presumed lost, so that fewer than 200 entries have been preserved to date, some of them in bad condition. Due to their historic and scientific importance, extensive efforts to preserve these specimens are more than justified. A significant number of 64 individuals, representing more than 37% of all specimens that were recorded in this survey, have never been published, and are reported here for the first time. Associated geographical data and collection dates are present for nearly all specimens. These ‘new historical records’ can add significantly to our knowledge of the Bramble sharks’ relative abundance and geographical distribution in time. These data will be included in the ongoing Bramble shark Cold Case, a project that will document its suspected decline, and to implement appropriate conservation measures for this iconic, little-known and endangered shark species.

LES ELASMOBRANCHES PLEUROTRÊMES DE LA CÔTE DU LANGUEDOC (FRANCE MÉRIDIONALE) : OBSERVATIONS BIOLOGIQUES ET DÉMOGRAPHIQUES

Article

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Jan 2000

Eastern Atlantic & Mediterranean Angel Shark Conservation Strategy

Technical Report

Full-text available

Jun 2017

The Eastern Atlantic & Mediterranean Angel Shark Conservation Strategy has been developed to act as a catalyst for conservation action for the three Critically Endangered angel sharks found in these regions - the Angelshark (Squatina squatina), Sawback Angelshark (S.aculeata), and Smoothback Angelshark (S. oculata).

Population structure, distribution and habitat use of the Critically Endangered Angelshark, Squatina squatina, in the Canary Islands

Article

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May 2017

Angel sharks are among the most threatened fish worldwide, facing regional and global extinction. In Europe, populations of the three Critically Endangered angel sharks ( Squatina aculeata , Squatina oculata and Squatina squatina ) have been severely depleted. Taking advantage of the last global ‘hotspot’ of the angelshark, Squatina squatina , this study gathered data through a citizen science programme to describe the occurrence of this shark in the coastal waters of the Canary Islands. Specifically, this study described (1) the population structure, and (2) habitat use of this species, which was used in a Species Distribution Model to (3) examine realized and potential distribution patterns, and to (4) determine the relative importance of environmental predictors on the occurrence of S. squatina . Over the 12 months sampling period (April 2014 – March 2015), 678 sightings were reported. Individuals ranged from 20 to 200 cm (total length). Larger sightings of both females and neonates occurred mostly in April to July, i.e. during the pupping season. Males were significantly more frequent in November to January, i.e. during the mating season. Angelsharks were encountered at depths from <1 m to a maximum of 45 m. Small‐sized individuals (i.e. neonates) exclusively occurred in shallow water (0–25 m). Most sharks occurred on sandy bottoms adjacent to reefs. Even though sightings were recorded at all seven islands in the archipelago, there were fewer encounters in the western than the eastern islands. The Species Distribution Model indicated that the probability of occurrence mainly correlated with sea surface temperature, chlorophyll, salinity and depth. Areas with the greatest habitat suitability were in shallow water. The angelshark displayed spatial (vertical and horizontal) and temporal segregation by size and sex. This information is vital to inform conservation of this Critically Endangered shark in its last stronghold.

Common, rare or extirpated? Shifting baselines for common angelshark, Squatina squatina (Elasmobranchii: Squatinidae), in the Northern Adriatic Sea (Mediterranean Sea)

Article

Full-text available

Jun 2016
HYDROBIOLOGIA

Historical baselines are needed to reconstruct long-term changes in marine animal populations and enhance our ability to articulate management recommendations. We reconstructed common angelshark (Squatina squatina) abundance in the Northern Adriatic Sea over the last two centuries by integrating different sources of formal and informal information. The wide amount of information collected helped assessing if the species is actually extirpated from the area, as stated in previous studies. According to naturalists’ accounts and historical documents, in the nineteenth and early twenty-first centuries the species was so abundant to sustain targeted fisheries, and large quantities of S. squatina were sold in the main fish markets. In the 1960s, the species collapsed and got economically extinct. Even if it was never caught in the area through scientific surveys during the period 1948–2014, from fishermen interviews emerged that the species is not extirpated. However, only 50% of interviewees caught S. squatina at least once and they were significantly older than the fishermen that never caught it (shifting baseline syndrome). Moreover, the size of the fish caught significantly decreased through time, indicating the depletion of larger individuals. Our integrated approach can be applied to any poorly assessed species so that appropriate international conservation measures can be prioritized.

Status of angelshark, squatina squatina (Elasmobranchii: Squatiniformes: Squatinidae) in the sea of marmara

Article

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Jan 2014

On 4 January 2014, a female specimen of Squatina squatina was entangled in trammel-net, at a depth of about 50 m. The specimen was 174 cm long (total length) and weighed approximately 35 kg. The recent single capture of S. squatina in the southeastern Sea of Marmara confirms the contemporary presence of the species in this landlocked small marine region; however, the paucity of the species in the fishing records of Marmaric fishes since 2000, confirms its rarity in the studied marine area.

Making marine and coastal citizen science matter

Article

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Oct 2015

Against the backdrop of a dramatic increase in citizen science activity worldwide, we convened a combined symposium and focus group at the 2014 International Marine Conservation Congress to consider the challenges and opportunities for mobilizing citizen science in the marine and coastal environment. Highlighting the diversity of existing models and approaches to citizen science, participants focused on six different conservation-related outcomes that citizen science projects can potentially support: policy, education, community capacity building, site management, species management, and research. We provide two example case studies of projects and summarize the key themes and recommendations associated with each of those outcomes. The result is a series of “toolkits” that can help to guide new and existing citizen science projects that aim to support management and conservation of ocean resources, as well as providing insights and recommendations to stimulate further research on and assessment of marine and coastal citizen science programs. Citizen science is an effective approach to conservation and it is time for this underutilized resource to become a more prominent approach for marine and coastal conservation.

European Red List of Marine Fishes

Technical Report

Full-text available

Jun 2015

Aim | The European Red List is a review of the conservation status of European species according to IUCN regional Red Listing guidelines. It identifies those species that are threatened with extinction at the regional level, so that appropriate conservation action can be taken to improve their status. This Red List publication summarises results for all described native European marine fishes. Scope | All marine fishes, including all hagfish, cartilaginous fish and bony fish species native to or naturalised in Europe before AD 1500 (a total of 1,220 species), have been assessed in this Red List. The geographic scope encompasses the Mediterranean Sea, the Black Sea, the Baltic Sea, the North Sea and/or the European part of the Atlantic Ocean (i.e., the territorial waters and the Exclusive Economic Zones (EEZs) of all European countries in the Eastern part of the Atlantic Ocean, including the EEZs of the Macaronesian islands belonging to Portugal and Spain). Status assessment | The status of all species was assessed using the IUCN Red List Categories and Criteria (IUCN 2012a), which are the world’s most widely accepted system for measuring extinction risk. All assessments followed the Guidelines for Application of IUCN Red List Criteria at Regional and National Levels (IUCN 2012b). These assessments were compiled based on the data and knowledge from a network of leading European and international experts on marine fish. The assessments were then completed and reviewed at three large workshops held in Spain, Belgium and the UK, as well as through email correspondence with relevant experts. More than 110 experts participated in the assessment and review process for European marine fishes. Assessments are available on the European Red List website and data portal: http://ec.europa.eu/environment/nature/ conservation/species/redlist and http://www.iucnredlist. org/initiatives/europe. Results | Overall, 7.5% of the total of European marine fish species that were assessed in this study are considered threatened (i.e., assessed as having an elevated risk of extinction) in European waters. A further 2.6% (26 species) are considered Near Threatened. However, for 204 species (20.6%), there was insufficient scientific information available to be able to evaluate their risk of extinction and thus they were classified as Data Deficient (DD). When more data become available, some of these species might also prove to be threatened. By comparison, of those other groups that were assessed comprehensively in Europe, 59% of freshwater molluscs, 40% of freshwater fishes, 23% of amphibians, 20% of reptiles, 17% of mammals, 16% of dragonflies, 13% of birds, 9% of butterflies and bees, 8% of aquatic plants and 2% of medicinal plants are threatened (IUCN 2011a, Nieto et al. 2014, Allen et al. 2014, BirdLife International 2015). Additional European Red Lists assessing a selection of species showed that 22% of terrestrial molluscs, 16% of crop wild relatives and 15% of saproxylic beetles are also threatened (IUCN 2011a). No other groups have yet been assessed at the European level. Looking at the population trends of European marine fish species, 8.4% (83 species) have declining populations, 21.5% (212 species) are more or less stable and 1.7% (17 species) are increasing. The population trends for 676 species (68.4%) remain unknown. Eight of the 184 species (4.3%) that are endemic to Europe (i.e., they are found nowhere else in the world) are threatened (Critically Endangered, Endangered, or Vulnerable), highlighting the responsibility that European countries have to protect the global populations of these species. Overall, the European areas with the highest diversity of species are the coast of Portugal, the Macaronesian islands and the western Mediterranean Sea. Hotspots of endemic species are found in the Mediterranean Sea, in particular along the European coast, including the Balearic, Ligurian, Tyrrhenian, Adriatic and Aegean Seas. Furthermore, the greatest concentrations of threatened species appear off the Iberian Peninsula, the Mediterranean Sea and the Canary Islands. Finally, the highest number of Data Deficient (DD) species is present near the Macaronesian islands, particularly in the Madeiran and Canarian archipelagos. The main threats to European marine fishes are overfishing, coastal development, energy production and mining, and pollution. Recommendations • Use the European and national Red Lists of marine fishes to inform revisions and implementation of relevant European legislation (including the Marine Strategy Framework Directive and the Maritime Spatial Planning Directive) to improve the status of threatened marine species, and to improve the knowledge of Data Deficient species. • Continue, and where necessary, expand multi-national fisheries conservation initiatives and management of commercially shared stocks of exploited species, particularly in the Mediterranean and Black Seas. • Take immediate measures to (i) reduce target and incidental catches of species assessed as threatened (i.e., Critically Endangered, Endangered and Vulnerable), (ii) enact measures to ensure sustainable management of species threatened by exploitation, and (iii) set and enforce science-based fishing opportunities and multi-annual management plans for all commercial species, especially those fisheries that target or affect species assessed as threatened and Near Threatened based on exploitation. • Ensure compliance with the requirements under the Common Fisheries Policy (CFP) to apply the precautionary approach by harvesting species at levels to ensure Maximum Sustainable Yield (MSY) for all EU fisheries, especially those for highly migratory species. • Ensure compliance with the requirements, under the Common Fisheries Policy (CFP) to apply the ecosystem-based management of fisheries. • Improve collection of fisheries-dependent data of commercial fisheries, in particular data on catch composition, by-catch, landings, discards, and catch per unit effort, and where not already in place, establish monitoring schemes for small scale artisanal and recreational (line and spear) fisheries. • Require fully documented fisheries and proper mapping of fisheries and fishing effort deployed though control technologies such as Vessel Monitoring System (VMS), Vessel Detection System (VDS) and/ or Automatic Identification System (AIS). • Expand fisheries-independent data collection monitoring, especially for Data Deficient species, and monitoring of threatened species that are not 6 currently sampled effectively, and ensure that such data are exchanged with relevant scientific bodies and Regional Fisheries Management Organisations (RFMO) (e.g., ICES, GFCM, NEAFC, ICCAT). Improve EU and RFMO requirements for speciesspecific reporting of catches and landings of all species, especially chondrichthyans, and for quality assurance of these data so that improved analyses of long-term trends can be undertaken. • Carry out analyses of species trends in both the Northeast Atlantic and the Mediterranean Sea. In particular in the Mediterranean Sea, although there is the ongoing MEDITS survey, there is an urgent need for the development of region-wide time-series analyses of these data. • For those taxa with threatened species and taxonomic problems, improved species identification is required in all data collection exercises (including both commercial landings as well as scientific surveys). For that purpose, trainings of species identification to fishers should be provided, in particular for sharks, skates and rays species, with a view to ensuring that these species are not confused and that juveniles in particular can be distinguished. • Ensure that all designated Marine Protected Areas (MPAs) and areas restricted to fisheries, at the national, regional (Regional Seas Conventions) and European levels (Natura 2000 network) provide adequate protection to threatened marine fishes and particularly protect critical habitats for key life cycle stages (e.g., spawning, pupping, nursery and feeding grounds). • Fully adopt and enforce fisheries management measures for designated MPAs with the view to alleviate pressure on marine fish species and on the habitats that are necessary for their conservation. • Expand area-based conservation measures to meet and exceed the globally agreed-upon Aichi Target 11 of 10% coverage of each marine region, by identifying and establishing Fish Stock Recovery areas, as per the Common Fisheries Policy provisions, to protect spawning grounds and concentration of juvenile fish for those commercial fish species assessed as Critically Endangered, Endangered, Vulnerable and Near Threatened. • Revise the list of threatened European marine fishes regularly, and whenever new data becomes available. • Conduct basic biological research for deep-sea and Data Deficient species, especially those that are or have been commercially exploited (e.g., Orange Roughy, Hoplostethus atlanticus, and the wolf-fishes, Anarhichas spp.).

Reproduction and Development of the Pacific Angel Shark, Squatina californica, off Santa Barbara, California

Article

Full-text available

Dec 1986
COPEIA

Specimens of Squatina californica were collected from commercial gill-net boats off Santa Barbara, California, from Jan.-Nov. 1983 for studies of reproduction. Sexual maturity in both males and females began between 900 and 1000 mm TL. Fecundity estimates from egg and embryo numbers ranged between 1 and 11. The number of young did not increase with increasing size of the female after maturity. Reproduction in the angel shark appears to follow an annual cycle. Embryo size from samples of pregnant females taken in eight months increased gradually for the 12 months between Aug. and July. Pupping occurred in spring and each female had an average of six pups. Growth rates ranged from 45 mm TL per month in very young embryos to 10 mm TL per month in those approaching the size at birth and the overall mean growth rate was 23 mm TL per month. Individual developmental morphology is described for five embryos ranging in size from 35.4-175 mm TL.

Estimation and analysis of biological parameters in elasmobranch fishes: a comparative life history study

Article

Full-text available

May 2001
CAN J FISH AQUAT SCI

Published life-history parameters for sharks, skates, and rays over a wide geographic range were used to develop predictive models to estimate parameters that are difficult to measure or have not been previously estimated in elasmobranch species. We determined empirical relationships between body size (total length) and length at maturity (L m ) and age at maturity (T m ). The data used in determining these empirical relationships, the von Bertalanffy parameters asymptotic length (L [Formula: see text] ) and growth rate (k), and natural mortality (M) and maximum age (T max ) were used to describe the life-history strategies of elasmobranch fishes. M/k and Beverton's growthmaturitylongevity plots were used to make comparisons between teleost fishes, reptiles, and elasmobranchs. We found that the M/k ratio in elasmobranchs is significantly different from those for other fish and reptile taxa. We linked elasmobranch species fecundity (f) and T m to potential vulnerability to population decline under exploitation. We found that larger species of elasmobranchs have lower growth rates (k) and potential population increases (r'). Elasmobranchs can be categorized by species maximum length to determine susceptibility of decline under exploitation. Generally, species greater than 100 cm are characterized by life-history and population traits that place them at greater risk of population decline.

Extinction risk and conservation of the world's sharks and rays. eLife 2014;3:e00590

Data

Full-text available

Jan 2014

New data on the occurrence of the critically endangered common angelshark, Squatina squatina, in the Croatian Adriatic Sea

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