Differences in growth performance between Arcto‐Norwegian and Norwegian coastal cod reared under identical conditions

Abstract

Offspring from seven family groups of Arcto-Norwegian cod (AN) and a genetically marked Norwegian coastal cod (NC) broodstock, were mixed at metamorphosis and raised in the same rearing unit. The fish were transferred subsequently to a net-pen and held under standard farming conditions. In December 1992, 466 cod juveniles were measured, weighed, and tagged individually. Length and weight changes were monitored until the fish matured (January 1994). Genotyping of each individual was performed using enzyme electrophoresis to identify the fish to strain. Prespawning females were examined for organ weights and stage of maturity. There were population specific differences in growth performance. NC displayed significantly higher specific growth rate (SGR) and daily length increment (DLI) during spring/summer season. The AN had significantly lower hepatosomatic and gonadosomatic indices, and were thinner than the NC, indicating differences in body form and energy allocation pattern between the two strains. All NC (both sexes) became sexually mature at the age of 2 years while 2% of fish in the AN group were still immature at the end of the experiment. 1996 The Fisheries Society of the British Isles

Sub-populations of coastal cod with different behaviour and life-history strategies

“…Cod develop through pelagic egg and larval stages with vertical distributions in the intermediate dynamic water masses (0 to 50 m depth), potentially causing a wide dispersal of early life stages by non-local, wind-driven transport, which allows advection between fjords and coastal areas (Asplin et al 1999). For cod in Norwegian waters the classic view is that there are only 2 major populations: the Northeast Arctic and the coastal cod populations, which differ in growth performance (Svåsand et al 1996). The Northeast Arctic population has its nursery area in the Barents Sea and undertakes yearly spawning migrations from the Barents Sea to the north Norwegian coast from 7 to 8 yr of age (Bergstad et al 1987, Nordeide & Pettersen 1998.…”

“…The North Atlantic cod (Gadus morhua L.) consists of many populations and sub-populations with different life histories, which are distributed on the west and east coast of the North Atlantic (Mork et al 1985, Brander 1994b, Bentzen et al 1996, Svåsand et al 1996, Fevolden & Pogson 1997, Ruzzante et al 1998, Jonsdottir et al 2002. Populations in warm water grow faster and mature earlier than those in colder water (Hutchings et al 1993, Brander 1994b.…”

Fecundity and growth of Atlantic cod (Gadus morhua L.) along a latitudinal gradient

“…However, experiments with Barents Sea cod in tanks (Svåsand et al, 475 1996) also suggest that at a large part of the reason for this is a direct physiological 476 response to high temperature and growth. Barents Sea cod females in aquaculture 477 have been reported to mature at an age of 2 years and at an average length of 45 cm 478 (Svåsand et al, 1996). 479…”

Evaluacion de la primera madurez sexual del huachinango del Pacifico (Lutjanus peru) nacido en cautiverio

“…Los peces en cautiverio, a menudo presentan una maduración temprana, dada la disponibilidad constante de alimento, así como la eliminación de presiones por depredación y pesca (Svåsand et al, 1996). Sin embargo, en poblaciones silvestres sometidas a explotación, se ha observado una notable disminución tanto de edad como de la talla de la primera madurez, como es el caso del bacalao Gadus morhua (Chen & Mello, 1999), arenque Clupea harengus (Engelhard & Heino, 2004) y salmón Oncorhynchus keta (Morita et al, 2005;García de Leaniz et al, 2007), como una respuesta fenotípica de la primera madurez a las presiones del medio.…”