Distribution and abundance of the life stages of the blue shark Prionace glauca in the Southwest Atlantic

Population structure, distribution and relative abundance of the blue shark (Prionace glauca) in the Caribbean Sea and adjacent waters of the North Atlantic

“…This can probably be attributed to several factors related to the distribution of blue sharks and variation in fishing practices. It has been determined that blue shark catch rates have shown a general increasing trend with increasing latitude in Australian waters (Stevens, 1992), a similar trend was also observed in the South Atlantic where blue shark catch rates in tropical waters were lower than those observed in subtropical and temperate waters (Hazin et al, 1998;Montealegre-Quijano and Vooren, 2010;Pons and Domingo, 2009). Fishing practices for swordfish are normally limited to soak times during the night with the help of light-sticks; while for big eye tuna is the use of deep (300 m) setting longline gear soaked during daytime.…”

“…Therefore, the constant incidence of juveniles throughout the years, particularly in the Caribbean Sea during the last trimester, and the presence of pregnant females close to parturition could suggest the southern Caribbean Sea as a potential area for parturition. Parturition areas for blue shark inferred from the abundance of small juveniles (<130 cm FL) have been suggested to be under the influence of the Arctic Convergence in the North Pacific and northwest Atlantic, and the Subtropical Convergence in the southwest Atlantic in waters at temperatures of 8-21 • C (North Pacific), 12-23 • C (northwest Atlantic), and 16-18 • C (southwest Atlantic) (Nakano and Nagasawa, 1996;Simpfendorfer et al, 2002;Montealegre-Quijano and Vooren, 2010). In the northeastern Atlantic, parturition areas inferred important catch rates of young-of-the-year blue sharks occur off the Iberian Peninsula, particularly off Portugal and Bay of Biscay (Nakano and Stevens, 2008;Aires-da-Silva et al, 2008a) in waters over a broad range of temperature profiles (∼7-27.6 • C) (Queiroz et al, 2012).…”

Distribution patterns and population structure of the blue shark (Prionace glauca) in the Atlantic and Indian Oceans

“…Nakano, ), reproductive state, sex and size segregation (e.g. Kohler, Turner, Hoey, Natanson, & Briggs, ; Montealegre‐Quijano & Vooren, ; Nakano & Seki, ; Pratt, ; Strasburg, ). The reasons for the specific differences detected in the blue shark distribution patterns seem to be mainly related to migratory and habitat segregation patterns, which are in turn related to spatio‐temporal changes in growth and reproductive stages.…”

“…Some previous studies have focused on the distribution of catch rates of blue shark in specific areas of the Atlantic, including the works of Hazin, Boeckmann, Leal, Lessa et al. (), Mejuto and García‐Cortés (), Domingo, Mora, and Cornes (), Montealegre‐Quijano and Vooren () and Carvalho et al. () in the south‐west Atlantic; Cortés, Brown, and Beerkircher () and Tavares, Ortiz, and Arocha () in the western North Atlantic; Megalofonou, Damalas, and DeMetrio () in the Mediterranean; and Vandeperre, Aires‐da‐Silva, Santos et al.…”

Juvenile Greenland sharks Somniosus microcephalus (Bloch & Schneider, 1801) in the Canadian Arctic

“…This strategy is considered to have evolved to partition habitats between young and adults/ large predators to minimize juvenile population mortality (Morrissey and Gruber 1993a;Heupel and Simpfendorfer 2002;Dibattista et al 2007). For pelagic species such as the blue (Prionace glauca) and silky (Cacharhinus falciformis) shark, juvenile habitat is less well defined and young are birthed offshore (Driggers et al 2008;Montealegre-Quijano and Vooren 2010). Young are often born at a larger size and litter size is larger (Cortés 2000); selective mechanisms thought to balance high rates of expected mortality (but see slow-reproducing sharks; Tsai et al 2010;Semba et al 2011).…”