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The main objective of the Working Group on Biological Parameters (WGBIOP) is to review the status, issues, developments, and quality assurance of biological parameters used in assessment and management. WGBIOP (1) plans workshops, exchanges, and validation studies on a range of biological varia-bles to review the quality of information supplied for stock assessment and improve quality as-surance and training; (2) investigates data availability and develops documentation and methods to improve communication between data collectors and end-users; (3) delivers new and im-proved functionality for the SmartDots platform. Four otolith exchanges and two workshops were completed in 2020–2021 using SmartDots— eight further exchanges are ongoing. Proposed future exchanges and workshops were reviewed and approved. The development of the SmartDots platform proceeded with the inclusion of the maturity, eggs, atresia, fecundity, and larval identification modules into the software version. A live SmartDots tutorial for event coordinators was conducted. Work to further develop quality assurance guidelines—and review national applications of these—progressed. Age and maturity validation studies were reviewed and a new method for prioritizing future validation work was proposed. Progress with the Stock Identification Database (SID) was reviewed, and the potential for creating a WGBIOP library collection and active involvement of WGBIOP in updating FishBase.org data were evaluated. The importance of identifying and documenting links be-tween all relevant databases and document repositories was identified, and a task to address this was initiated. Work on improving the feedback loop between data collectors and stock assessors on the usage and quality of biological parameters in stock assessment continued. Moving forward, WGBIOP aims to continue collaboration with WGALES and WGSMART on the development of the SmartDots platform, encouraging cross-group sharing of skills and ex-perience to optimize results. WGBIOP aims to improve accessibility to its outputs through up-dates to SID and FishBase.org, and the potential creation of a WGBIOP library collection. WGBIOP hopes to improve two-way communication between data collectors and end-users around the quality and utility of biological parameters used in assessment. WGBIOP also aims to amalgamate all validation activities into one coherent workstream., ICES

This Collective Article presents information on 17 taxa belonging to five (5) Phyla and extending from the Alboran Sea to the Levantine Sea. These new records were found in six (6) different ecoregions as follows: Alboran Sea: Second and easternmost record of the sponge Chalinula nigra in the Mediterranean Sea; Western Mediterranean: first record of the rare gobid Gobius couchi for Spain, based on both morphological and molecular data; new records for the rare ascidian Ciona edwardsi from the Marine Protected Area of Tavolara, Sardinia; several records for four (4) different species of black coral, Antipathella subpinnata, Antipathes dichotoma, Leiopathes glaberrima and Parantipathes larix from the Aeolian Archipelago, all of which are currently threatened and/or protected at a Mediterranean level; the first documented records of the sea lamprey Petromyzon marinus in Calabria, which is considered “Critically Endangered” in Italy; first record in the Tyrrhenian Sea and second record in the Ionian Sea for the crab Ocypode cursor, which seems to be rapidly expanding its distribution range across Italian waters; Adriatic Sea: Additional records of yellowmouth barracuda, Sphyraena viridensis, in the northern Adriatic, which seems to be experimenting a meridionalization process in the region; Aegean Sea: First confirmed record of the iconic gastropod Bursa scrobilator scrobilator in the eastern Mediterranean Sea; an additional record for the vulnerable shark Dalatias licha, also being the largest individual caught in eastern Mediterranean waters till the time of capture; an additional record for the rare crab Distolambrus maltzami, suggesting the species might be more morphologically variable than originally thought; first documented record for the myctophid Hygophum hygomii in both Turkish waters and the north Aegean Sea; additional records for the tuna Katsuwonus pelamis and the sunfish Ranzania laevis in the eastern Mediterranean, pointing out that both species might not be as rare in the area as previously thought; Levantine Sea: additional records for the rare stingray Taeniura grabata in Turkish waters. © 2021

The Collective Article on "New Mediterranean Biodiversity Records" offers the means to publish biodiversity records in the Mediterranean Sea. The current article presents new biodiversity data information on 18 taxa (14 alien, 3 native and 1 cryptogenic species) belonging to 5 Phyla that are reported for 11 different countries listed according to their geographic position from the western to the eastern Mediterranean Sea. Algeria: the alien green alga Caulerpa taxifolia var. distichophylla and the heterobranchs Aplysia dactylomeda and Aplysia punctata are first reported from the entire country. France: a new record of the alien hydroid Porpita porpita is reported from the Corsican Sea, representing the second record of the species in the western Mediterranean Sea. Tunisia: the alien fish Scatophagus argus is reported from the Gulf of Gabes, probably representing an aquarium release. Italy: the well-established Mediterranean alien bivalve Malleus regula is first reported from the entire country. Slovenia: the alien marine bivalve Xenostrobus securis is reported for the first time from the entire country. Croatia: the alien gastropod Biuve fulvipunctata is reported for the first time from the country but also from the entire Adriatic Sea. Montenegro: the alien bivalve Rapana venosa is reported for the first time from the Montenegrin waters. Albania: the well-established alien fish Lagocephalus sceleratus and the rare native shark Rhizoprionodon acutus are reported for the first from the entire country. Greece: the rare native ray Leucoraja circularis is reported for the first time from the Argolikos Gulf and for the first time for the entire country its identification is confirmed morphologically and molecularly; additional records of the alien nomad jellyfish Rhopilema nomadic document its expanding distribution, while the occurrence and the alien fishes Sillago suezensis and Pomadasys stridens are reported for the first time from Hellenic waters. Turkey: additional records of the Egyptian Prawn Metapenaeopsis aegyptia are reported with some biological information. Cyprus: the alien fish Variola louti is reported for the first time for the entire Mediterranean Sea, probably released from an aquarium, while the alien moon crab Matuta victor is reported for the first time from the entire country.

Understanding reproductive features of elasmobranchs that affect population recovery and natural mortality is essential for conservation management planning. Considering macroscopic and microscopic observations of the reproductive tract in 2253 individuals, sampled in Hellenic waters over a 7-year period, four reproductive stages were described. The presence of advanced spermatocyst stages in immature testes supported the early gamete development and long maturation process. The simultaneous presence of follicles of all developmental stages in mature ovaries indicated a protracted egg-laying season. An extended reproductive period was also supported by monthly records of egg-laying females, sexually active males, large egg cases and high values of the gonadosomatic (GSI) and hepatosomatic (HSI) indices. Size at maturity was similar for both sexes. Females and males exhibited no depth segregation compared with individuals of different maturity stages regardless of sex. Sex, size and maturity stage significantly affected GSI, HSI and the relative condition factor. All three somatic indices showed a similar monthly variation, supporting a fat assimilation rate that follows maturation rate, with both affecting physiological condition. The severe population decline that Scyliorhinus canicula has recently undergone should focus our attention on future research supporting robust population modelling to help management of the species. © 2020 CSIRO.

In this collective article we discuss the relationships between the otolith measurements (weight, radius) and total length of Mullus surmuletus in the Aegean and Ionian Seas and of Pagellus erythrinus samples caught in the Southern Aegean Sea. In addition to the above mentioned studies, the abundance of the rare fish Echiodon dentatus in the Kyklades and the Saronikos Gulf (Central Greece) is also documented. The first weight-length relationship of the alien northern brown shrimp Penaeus aztecus from the Central Aegean Sea is given at the end.

The population composition and aspects of the reproductive biology of 452 blackmouth catsharks, Galeus melastomus were investigated. The sharks were incidentally caught off the North-Western Aegean, the Eastern Corinthian and Northern Euboean Gulfs by commercial bottom trawlers and longlines at depths between 200 and 500 m. The overall sex ratio (1:1.1 females:males) was not different from the theoretical unit (1:1). No differences in the sex ratios were detected among seasons, areas or depth strata. Significant differences in the population structure regarding different maturity stage proportions at different seasons, fishing areas and depths, were observed. The sampled population mainly consisted of immature catsharks (77%), predominantly trawled off the NW Aegean and Corinthian Gulf during winter and autumn. Fifteen per cent of the samples, mainly captured in spring and summer off the N Euboean Gulf, were mature. Eight per cent of the specimens was found to be maturing. Higher frequencies of heavier female individuals were observed. Based on the maturation ogives and the total lengths (TL) for each sex, using logistic regression which presented sex-related differences, male Galeus melastomus achieved maturity at 433.6 mm while females at 483.5 mm. The number of egg capsules in the oviducts spanned from 1-12 per female with sizes varying from 38 × 14 mm to 55 × 20 mm. This is the first study investigating the demography and aspects of Galeus melastomus reproduction in the Eastern Mediterranean. © Copyright Marine Biological Association of the United Kingdom 2016.

This study concerns the cephalopod species that are part of the diet of the small-spotted catshark Scyliorhinus canicula and the longnose spurdog Squalus blainville sampled by commercial trawlers in the Aegean Sea from 2005 to 2012. Based on the examined cephalopod beaks, 15 species were identified belonging in six families of Teuthida, one of Sepiida and two of Octopoda. The diversity of cephalopod prey species was higher for S. canicula (N = 15) than for S. blainville (N = 10). Nektonic cephalopods comprised the majority (>72%) of the preyed species by both sharks, among which about 55% inhabit the demersal zone and 45% the mesopelagic. In the diet of S. canicula, the demersal squid Illex coindetii and the pelagic sepiolid Heteroteuthis dispar were equally represented composing 20% of prey specimens, followed by the small-sized squid Abralia veranyi and the demersal sepiolid Rossia macrosoma. The latter species was substituted in the diet of S. blainville by the demersal medium-sized octopod Scaeurgus unicirrhus, which with the equally represented three other species, composed 50% of the cephalopod prey. Differences observed between S. canicula and S. blainville in the condition of beaks retained in their stomach contents and in the variation of prey species diversity by predator specimen size, may imply differences in their foraging tactics (hunting for prey vs scavenging on the bottom), habitats and stomach evacuation frequency. Copyright © Marine Biological Association of the United Kingdom 2017.

The diet of the small-spotted catshark Scyliorhinus canicula, captured in the Aegean Sea by bottom-trawl from 2006 to 2012, was investigated with respect to sex, maturity condition, sampling location and season. The stomach contents of 432 specimens, measuring from 144 to 517 mm in total length, were analysed. The cumulative prey curve showed that the sample size was adequate to describe the species’ diet, which was quantified using the percentage gravimetric composition (%W). The identified prey items belonged to eight major groups: Teleostei, Chondrichthyes, Crustacea, Cephalopoda, Annelida, Echinodermata, phanerogams and macroalgae, with Teleostei, Crustacea and Cephalopoda being the most consumed in both females (%W = 48.1, 16.0 and 31.4, respectively) and males (%W = 33.9, 31.6 and 29.8, respectively). Higher diet diversity was observed in males than females, in immature individuals than mature ones, regardless of sex, as well as in spring in comparison to autumn and winter. Feeding intensity seemed to be influenced mainly by sex and maturity condition. No significant dietary overlap was observed for all possible combinations of the factors examined. Gut indices were compared between the two sexes with females showing statistically significantly higher median relative gut length, as well as a longer gut than males of the same length. Based on the diet composition, S. canicula can be considered a generalist predator consuming, with geographical differentiation, a wide variety of benthic taxa. The estimated fractional trophic level (τ = 4.22) classified the species as a carnivore with a preference for Teleostei and Cephalopoda, thus confirming its key role in the food web. © 2017 Informa UK Limited, trading as Taylor & Francis Group.

Knowledge of the diet and trophic level of marine predators is essential to develop an understanding of their ecological role in ecosystems. Research conducted on the trophic ecology of the deep-sea sharks is rather limited. The purpose of this study was to examine the diet of the longnose spurdog Squalus blainville, a deep-sea shark categorized as “data deficient” within its distribution range, with respect to sex, maturity, age, season and sampling location. The stomach contents of 211 specimens, captured in the Aegean (off Skyros and the Cyclades Islands) and Cretan Seas, using commercial bottom-trawlers from 2005 to 2012, were analysed. The cumulative prey curve showed that the sample size was adequate to describe the species’ diet. The identified prey items belonged to five major groups: Teleostei, Crustacea, Cephalopoda, Annelida and Phanerogams. Higher diet diversity was observed in females compared to males, in immature individuals compared to mature ones, regardless of sex, and in spring and winter compared to other seasons. Age and sampling location seemed to influence both the diet diversity and trophic spectrum of the species. Feeding intensity based on the vacuity index was not significantly influenced by any of the factors examined, while the stomach filling degree was significantly influenced by all factors, except sex, showing significantly higher values in mature females compared to immature ones, in older individuals, in autumn compared to winter, and a significantly lower value in the Cyclades Islands compared to other locations. Females showed a significant larger mouth length compared to males of the same length, while no between-sex differences were found in gut morphometrics. The estimated fractional trophic level (TROPH=4.41) classified the species as carnivore with a preference for Teleostei and Cephalopoda, confirming its high trophic position. © 2017 Elsevier Ltd

New records of the rare angular rough shark Oxynotus centrina from the Hellenic Seas are presented. Its occurrence is reported for the first time in the Corinthian Gulf. Some aspects of the species' biology are described and compared with previous studies. © 2016 The Fisheries Society of the British Isles.

Squalus blainville is one of the least studied Mediterranean shark species. Despite being intensively fished in several locations, biological knowledge is limited and no genetic structure information is available. This is the first study to examine the genetic structure of S. blainville in the Mediterranean Sea. Considering the high dispersal potential inferred for other squalid sharks, the hypothesis of panmixia was tested based on a 585 bp fragment of the mitochondrial DNA cytochrome c oxidase subunit I gene from 107 individuals and six nuclear microsatellite loci from 577 individuals. Samples were collected across the Ionian, Aegean and Libyan Seas and off the Balearic Islands. Twenty three additional sequences of Mediterranean and South African origin were retrieved from GenBank and included in the mitochondrial DNA analysis. The overall haplotype diversity was high, in contrast to the low nucleotide diversity. Low and non-significant pairwise FST and FST values along with a Bayesian cluster analysis suggested high connectivity with subsequent genetic homogeneity among the populations studied, and thus a high dispersal potential for S. blainville similar to other squalids. The historical demography of the species was also assessed, revealing a pattern of population expansion since the middle Pleistocene. These findings could be considered in species-specific conservation plans, although sampling over a larger spatial scale and more genetic markers are required to fully elucidate the genetic structure and dispersal potential of S. blainville.

Aging chondrichthyans has been characterized as a slow and difficult process, but at the same time it is considered of fundamental importance for the holistic management and conservation of their populations. This study aims to assess the age and growth of the longnose spurdog S. blainville, to correlate the results to the species' biological features and to compare them with those reported in previous studies that used different aging methods. By counting the growth bands on the enamel surface of the dorsal fin spines, age was estimated in 569 out of 810 individuals that were taken as by-catch from commercial fisheries in the Mediterranean Sea during an 8-year period. Spine morphometrics revealed sexual dimorphism as far as spine length, spine base width and spine weight are concerned. The between-sex differences were also reflected in the length-weight relationships, in the gonadosomatic (GSI) and hepatosomatic (HSI) indices, and in the condition factor (K). All three somatic indices differed significantly among maturity stages, seasons or age classes. The reproducibility of the age readings was considered high based on the estimated CV and APE precision indices. Age bias plots also indicated no significant intra- and small inter-reader variation. The estimated VBGF parameters were: L∞ = 1097.3 mm, k=0.03 yr-1 and t0=-5.58 yrs for females, and L∞=665.5mm, k=0.08 yr-1 and t0=-3.35 yrs for males. Likelihood ratio tests showed that all growth parameters were statistically significantly different between sexes (χ2 = 38.26, df = 3, P

Coastal and demersal chondrichthyans, such as the small-spotted catshark, are expected to exhibit genetic differentiation in areas of complex geomorphology like the Mediterranean Basin because of their limited dispersal ability. To test this hypothesis, we used a fragment of the mitochondrial cytochrome c oxidase subunit I gene and 12 nuclear microsatellite loci in order to investigate the genetic structure and historical demography of this species, and to identify potential barriers to gene flow. Samples were collected from the Balearic Islands, the Algerian Basin, the Ionian Sea, the Corinthian Gulf and various locations across the Aegean Sea. Additional sequences from the Atlantic and the Levantine Basin retrieved from GenBank were included in the mitochondrial DNA analysis. Both mitochondrial and nuclear microsatellite DNA data revealed a strong genetic subdivision, mainly between the western and eastern Mediterranean, whereas the Levantine Basin shared haplotypes with both areas. The geographic isolation of the Mediterranean basins seems to enforce the population genetic differentiation of the species, with the deep sea acting as a strong barrier to its dispersal. Contrasting historical demographic patterns were also observed in different parts of the species' distribution, most notably a population growth trend in the western Mediterranean/Atlantic area and a slight decreasing one in the Aegean Sea. The different effects of the Pleistocene glacial periods on the habitat availability may explain the contrasting demographic patterns observed. The current findings suggest that the small-spotted catshark exhibits several genetic stocks in the Mediterranean, although further study is needed. © 2015 Macmillan Publishers Limited.

The present work reports on the extended distribution of nineteen species in the Mediterranean. These are: Upeneus pori (Fish:Turkey), Bursatella leachii (Mollusca, Opisthobranchia: eastern coast of Spain), Sparisoma cretense (Fish: Ionian coast of Greece), Pseudobryopsis myura (Chlorophyta:Turkey), Aplysia dactylomela (Mollusca, Opisthobranchia: Karpathos island, and Kyklades Archipelago, Greece), Asparagopsis armata and Botryocladia madagascariensis (Rhodophyta: South Peloponnesos, Greece), Oxynotus centrina (Fish: Greece), Caulerpa racemosa var. cylindracea (Chlorophyta), Stypopodium schimperi (Phaeophyta) Siganus luridus and Stephanolepis diaspros (Fish) Percnon gibbesi (Decapoda, Brachyura) (Kyklades Archipelago, Greece), Cerithium scabridum (Mollusca, Prosobranchia: Anavissos: Greece) and Cerithium renovatum (Mollusca, Prosobranchia: N. Kriti), Cassiopea andromeda (Scyphomedusa: Rhodos Island, Greece), Abra tenuis (Mollusca Bivalvia: Vouliagmeni Lake, Greece) Lagocephalus lagocephalus (Fish: Calabrian coast, Italy) and Plocamopherus ocellatus (Mollusca, Opisthobranchia: Iskenderun Bay, Turkey).

A total number of 526 Squalus blainvillei was sampled from the bottom trawl and bottom longline catches in the eastern Mediterranean Sea from December 2004 to December 2009. Females outnumbered males and the overall sex ratio was 1.26:1. Females ranged from 182 to 779 mm in total length and males from 180 to 799 mm. Both females and males showed allometric growth (b>3) and we found statistically significant differences in the relationship between length and weight. Out of the specimens examined, 36% of females and 63% of males were sexually mature. Males reached sexual maturity at smaller sizes than females. The smallest sexually mature female was 523 mm in total length, while the smallest sexually mature male was 425 mm in total length. Mean length at 50% maturity was estimated at 564.4 mm for females and 457.7 mm for males. Sexually mature specimens of both sexes with mature gonads and high GSI were present in high proportions in every season of the year, which indicates a continuous reproductive cycle. Ovarian oocytes continued to develop throughout gestation. Females carrying near-term embryos had large, equally developed ovarian oocytes, which suggests that they ovulate soon after parturition. Ovarian fecundity ranged from 1 to 7 and uterine fecundity ranged from 1 to 6. Embryo length and yolk sac weight were negatively correlated.

A total of 325 small-spotted catsharks, Scyliorhinus canicula, ranging from 263 to 488 mm in total length (TL) and from 62 to 395 g in round weight (RW), were sampled from trawl catches in the Aegean Sea during the two-year period 2005-2007. The overall ratio of males to females was 1.06:1, and of the specimens almost 60% were mature. The size of mature males and females ranged between 371-488 mm and 364-467 mm in total length, respectively, while total length at 50% maturity was estimated at 396 mm for males and 399 mm for females. Ovary weight varied from 0.1 to 25.4 g and maximum oocyte diameter was 18 mm. Gonadosomatic indices ranged from 0.13 to 9.77 in female fish and from 0.25 to 6.36 in male fish, showing significant seasonal changes only in females (p-value < 0.05). Ovarian fecundity reached a maximum of 18 ripe oocytes in the ovary of a 460 mm TL female. Only one pair of egg cases was found in each one of the 30 adult females examined. © 2010 Taylor & Francis.

In September 2015, the Working Group on Biological Parameters (WGBIOP) recommended an otolith exchange for Mullus surmuletus and Mullus barbatus in 2016 (Otolith Exchanges proposals for 2016/2017; ICES, 2015). Kélig Mahe (IFREMER, France) was decided to be the responsible to organise this otolith exchange. Two otolith exchanges (2008, 2011), and two age reading workshops (ICES, 2009; 2012), have been taken place until now (Mahé et al., 2012). A total of 13 readers from 5 countries (France, Spain, Italy, Cyprus and Greece) participated at the exchange of 2016. The otoliths of 465 individuals (345 M. barbatus & 120 M. surmuletus), sampled from 2011 to 2014 in the Mediterranean Sea (Central Adriatic Sea, Cyprus, Levantine Spain coasts, Balearic Islands) were used for this exchange. For both Mullus species, the precision values were very low, the PA ranged between 56 and 67% the CV ranged from 32 to 64% and the APE ranged from 1.9 to 3.6%. The results by area and species showed the same trend with the first age groups presenting the higher CV values and in some cases lower PA values. These results could be explained by the position of the first growth increment and the two different approaches of reading interpretation used by the readers (ICES, 2012).