![]() The maximum size ranges from 10-cm total length (TL) for the short-nose electric ray Narcine laticaudus ( Froese and Pauly, 2015) to 910 cm disc width (DW) for the manta ray Mobula birostris ( White et al., 2006). Size and life history parameters of skates and rays vary in wide range. The aforementioned measures highlighted the urgency of conservation and management of skates and rays. ( Anon., 2016) and the guitarfish Rhinobatidae and wedgefish Rhinidae ( Anon., 2019) on its Appendix II list. The Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) has placed the sawfishes on its Appendix I list ( Anon., 2013) and the manta rays and the devil rays Mobula spp. These results clearly indicated that species-specific stock status information is urgently needed to ensure the sustainable utilization of skate and ray stocks.Īccording to the International Union for Conservation of Nature (IUCN) red list criteria, 10% of chondrichthyes fall in the category threatened (including critical endangered, endangered, and vulnerable), of which 40% are sharks and 60% are skates and rays. The decline of large skates coupling with an increase in the abundance of small skates in the northeast Atlantic resulted in a structural change in the marine ecosystem ( Dulvy et al., 2000). However, the development of fishery management plans for skates and rays is difficult due to the lack of detailed biological information and species-specific catch data ( Stevens et al., 2000) because most of them are of low economic value. With the increase in skate and ray catches, it is necessary to develop management plans of these species to ensure sustainable use of these resources ( Dulvy and Reynolds, 2002). Recent assessments of global oceanic rays suggested that several species have been overexploited or have even collapsed ( Pacoureau et al., 2021). The global landings of skates and rays reported to the United Nations Food and Agriculture Organization (FAO) declined almost 20% from 2003 to 2012 ( Davidson et al., 2016). These skates and rays are vulnerable to anthropogenic pressure and may decline or collapse after experiencing heavy fishing pressure ( Hoff and Musick, 1990 Musick, 1999). Excluding manta rays and butterfly rays, most skates and rays inhabit coastal demersal waters and play an important role in the demersal ecosystem ( Ebert and Bizzarro, 2007). ![]() Many batoids, similar to sharks, have the life history characteristics of slow growth, late maturity, and low numbers of offspring ( Ebert and Sulikowski, 2009). The λ′ values estimated by these empirical equations showed good agreement with those calculated using conventional demographic analysis, suggesting that this approach can be applied in the implementation of management measures for data-limited skates and rays in a precautionary manner. Group 1 included species with slow growth rates ( k 25 years) Group 2 included species with intermediate growth rates (0.080 year –1 0.60) Group 3 included species with a fast growth rate ( k > 0.160 year –1), short longevity ( T max 0.18). Empirical equation was developed for each group to describe the relationships between the predicted a finite rate of population increase (λ′) and the life history parameters: growth coefficient ( k), asymptotic length ( L ∞), age at maturity ( T m), annual fecundity ( f/ R c), ratio between size at birth ( L b), and L ∞ ( L b/ L ∞), and ratio between size at maturity ( L m) and L ∞ ( L m/ L ∞). Three groups were categorized by cluster analysis (CA) based on principal component scores. The life history (age and growth and reproduction) parameters of 35 species (41 stocks) of skates and rays were analyzed using multivariate analyses.
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