No abstract

No abstract

No abstract

Fish populations are often treated as homogeneous units in typical fishery management, thereby tacitly ignoring potential intraspecific variation which can lead to imprecise management rules. However, intraspecific variation in life-history traits is widespread and related to a variety of factors. We investigated the comparative age-based demography of the two main colour patterns of Labrus bergylta (plain and spotted, which coexist in sympatry), a commercially valuable resource in the NE Atlantic. Individuals were aged based on otolith readings after validating the annual periodicity of annuli deposition. The relationships between the otolith weight and fish age and between otolith length and fish length were strong but differed between colour patterns. The fit of the growth models to the age and length data resulted in divergent growth curves between colour morphotypes and between sexes. Males and spotted individuals attained larger mean asymptotic sizes (Linf) than females and plain individuals, respectively, but converged to them more slowly (smaller k). Estimates of mortality based on catch curves from two independent datasets provided a global total mortality (Z) of 0.35 yr–1, although Z was larger in plain and female individuals. Overall, the results of this research have direct implications for management of L. bergylta and, as a precautionary measure, we recommend considering both colour patterns as two different management units.

The observed Centrophorus granulosus were caught with bottom trawl and longline between 500 and 1300 m depth off the continental slope of Galicia and the Galician Bank (north-eastern Atlantic) between 1996 and 1998. The main biological data obtained were: a maximum recorded size of 166 cm TL (total length); females mature at 147 cm TL; between 1 and 10 mature oocytes by females of 55–80 mm diameter and as many as 6 pups per litter, and size at birth ranging between 35–47 cm TL. These results differ greatly from those compiled in the literature suggesting different populations or perhaps a possible misidentification.

Four new ¢sh species have been recorded for the ¢rst time in the last few years in Galician waters: Physiculus dalwigkii, Neoscopelus microchir, Gaidropsarus granti and Pisodonophis semicinctus. The captures of Physiculus dalwigki, N. microchir and G. granti represent a new northern limit for their distribution in the north-east Atlantic, increasing their geographical range of distribution considerably while the capture of Pisodonophis semicinctus is the second record for the Atlantic European waters.

The taxonomy of ceratioid fishes is challenging and frequently based on a small number of female specimens described for each species. Twenty ceratioid specimens caught on Flemish Cap and Grand Bank (western North Atlantic), representing 12 species and six families: Ceratias holboelli and Cryptopsaras couesii (Ceratiidae); Himantolophus albinares (Himantolophidae); Melanocetus johnsonii (Melanocetidae); Lophodolos acanthognathus, Oneirodes eschrichtii, Dolopichthys karsteni, and Leptacanthichthys gracilispinis (Oneirodidae); Caulophryne polynema (Caulophrynidae); and Haplophryne mollis, Linophryne brevibarbata, and L. bicornis (Linophrynidae) were identified by examination of morphological characters. DNA barcode sequences, from the 5′ end of the COI mitochondrial gene, were developed for 18 specimens and compared with all ceratioid barcode sequences available in public repositories. The analyses extended the ranges of some quantitative traits for certain species, highlighted the possible existence of cryptic species in C. couesii with distinct ranges in the Atlantic and Pacific oceans, and indicated a close relationship between Bertella and Dolopichthys meriting further attention. The authoritative identification of the 18 voucher specimens made possible detection of erroneous identifications of some sequences extracted from the repositories and highlighting of taxonomic conflicts that should be the subject of future studies.

No abstract