Thermal dynamics of ovarian maturation in Atlantic cod (Gadus morhua)

Kjesbu, Olav Sigurd; Righton, David; Krüger‐Johnsen, Maria; Thorsén, Anders; Michalsen, Kathrine; Fonn, Merete; Witthames, Peter R.

doi:10.1139/f10-011

Cited by 106 publications

(114 citation statements)

References 69 publications

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“…S1 and Table S1), during the vitellogenic prespawning period (19,42). We measured total length of each fish and whole-body, gonad, and liver weight, to indicate energy reserves (e.g., ref.…”

Section: Methodsmentioning

confidence: 99%

Frequent skipped spawning in the world’s largest cod population

Skjæraasen

Nash

Korsbrekke

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

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Life-history theory suggests that animals may skip reproductive events after initial maturation to maximize lifetime fitness. In iteroparous teleosts, verifying past spawning history is particularly difficult; the degree of skipped spawning at the population level therefore remains unknown. We unequivocally show frequent skipped spawning in Northeast Arctic cod (NEAC) in a massive field and laboratory effort from 2006 to 2008. This was verified by postovulatory follicles in temporarily arrested ovaries close to the putative spawning period. At the population level, "skippers" were estimated to be approximately equally abundant as spawning females in 2008, constituting ∼24% of the females 60-100 cm. These females never truly started vitellogenesis and principally remained on the feeding grounds when spawners migrated southward, avoiding any migration costs. The proximate cause of skipping seems to be insufficient energy to initiate oocyte development, indicating that skipped spawning may partly be a density-dependent response important in population regulation. Our data also indicate more skipping among smaller females and potential tradeoffs between current and future reproductive effort. We propose that skipped spawning is an integral life-history component for NEAC, likely varying annually, and it could therefore be an underlying factor causing some of the currently unexplained large NEAC recruitment variation. The same may hold for other teleosts.codfish | population dynamics | reproductive biology | total egg production | stock reproductive potential P opulation demography changes according to reproduction and mortality. In high latitude marine ectotherms, including teleosts, survival of the youngest age classes varies substantially, resulting in large fluctuations in population size (1). Historic spawning stock biomass (SSB) is used to forecast future fish recruitment, although the amount of unexplained variation indicates that SSB may not accurately reflect offspring production (2, 3). One factor that could significantly impact egg production is skipped spawning-the failure of iteroparous spawners to use each spawning opportunity after sexual maturity sensu (4). For most teleosts this phenomenon and its impact on population demography has received scant attention, but theoretical models indicate that up to 30% of the mature individuals may skip spawning and that it is an adaptive strategy optimizing lifetime fitness (5). To date, skipped spawning has been documented in more than 30 species (4, 6), including freshwater (7), marine (8), and anadromous teleosts (9). It has been documented for fish with both indeterminate and determinate fecundity and sequential hermaphrodites (6) and in species with as diverse life histories as the European horse mackerel Trachurus trachurus (10) and the orange roughy Hoplostethus atlanticus (8). Given the difficulty in conclusively establishing past spawning, reports of skipped spawning in teleosts are commonly anecdotal (4).The major process of energy transfer and oocyte gr...

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Section: Methodsmentioning

confidence: 99%

Frequent skipped spawning in the world’s largest cod population

Skjæraasen

Nash

Korsbrekke

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

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“…The samples were used to determine sex ratio, reproductive status (see below for assessment), gonad size, fecundity and timing of spawning. Morphometric measures included total Fecundity and hatching time was examined for 2 yr old fish from 3 farms following the methods outlined in Thorsen & Kjesbu (2001) and Kjesbu et al (2010) (Table 1). In short, fecundity and spawning time was determined by collecting ovarian tissue that was fixed in 3.6% phosphate-buffered formaldehyde.…”

Section: Extent Frequency and Timing Of Spawning Of Atlantic Codmentioning

confidence: 99%

“…Automated image analysis (ImageJ, available at: http:// rsb.info.nih.gov/ij) was subsequently used for measuring oocyte diameter for oocytes being > 200 µm. Of the 200 normal (vitellogenic) oocytes measured per sample, the largest 10% were defined as the leading cohort (LC) and the corresponding mean oocyte diameter used to predict time of start of spawning (calendar day) according to Kjesbu et al (2010). Individual potential fecundity (i.e.…”

Section: Extent Frequency and Timing Of Spawning Of Atlantic Codmentioning

confidence: 99%

“…standing stock of oocytes, F p ) was determined from oocyte packing density (number of oocytes g -1 ), estimated from the mean diameter of all 200 oocytes measured in each sample, multiplied by whole ovary weight (Thorsen & Kjesbu 2001). As F p decreases throughout gonadal development due to atresia (Kjesbu et al 2010), the standing stock of oocytes immediately before spawning would be lower than the F p calculated from samples collected at various points in time prior to spawning. To adjust for atresia a linear regression between calculated F p and LC (F p = -8676LC + 10 000 000, r 2 = 0.28) was used to estimate the standing stock of oocytes (oocytes at spawning = F p -[(800 -LC) × 8676]) for an assumed average LC oocyte diameter at spawning (800 µm).…”

Section: Extent Frequency and Timing Of Spawning Of Atlantic Codmentioning

confidence: 99%

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Extent and ecological importance of escape through spawning in sea-cages for Atlantic cod

Uglem¹,

Knutsen²,

Kjesbu³

et al. 2012

Aquacult. Environ. Interact.

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The culture of certain fish species to sizes at which they can reproduce has led to the escape of fertilised eggs or 'escape through spawning'. To investigate the extent and ecological importance of spawning in sea-cages for Atlantic cod Gadus morhua (L.), we (1) evaluated the extent, frequency and timing of spawning in cod culture; (2) analysed the quality of eggs released from farms in terms of variation in fatty acids; (3) modelled the distribution of eggs and larvae from a commercial cod culture site; and (4) predicted the post-escape survival of eggs through summarizing existing knowledge on survival rates of different life stages. Collectively, our results indicate that cod farming has the potential to produce large amounts of eggs and larvae through spawning in cages, with numbers of eggs spawned being 4 to 5 times higher in the second than in the first year. Our scenarios suggest that a typical sea-cage with 60 000 fish may produce 1.4 to 21 tons of 3 yr old first generation farmed cod through spawning in sea-cages. The quality of escaped eggs and larvae is likely to be sufficient for larvae to survive until the first feeding, while survival until adulthood, though difficult to predict, may be high under favourable conditions. Simulations indicate that eggs and larvae from farms may mix with those of wild fish during the spawning season, and thus experience comparable larval environments. However, several implementable management measures exist that will diminish the extent of egg escape in future cod farming.

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“…The discrepancy was probably caused by the difference in temperature regime from the Adriatic Sea, Mediterranean and Atlantic. Namely, according to Kjesbu et al (2010), the differences in temperature are probably a major driving force for the differences that are noticed in size at maturity and fecundity. It is known that fecundity varies annually (Sinovčić 1983(Sinovčić -1984Rijnsdorp 1991;Kjesbu et al 1998).…”

Section: Histologymentioning

confidence: 99%

The reproductive cycle, size at maturity and fecundity of garfish (Belone belone, L. 1761) in the eastern Adriatic Sea

2010

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A recent study concerning the reproductive biology of the garfish (Belone belone, L. 1761) has been carried out in the eastern part of the Adriatic Sea along the Croatian coastline. Specimens of the fish (N = 3,393) were collected over a 6-year period (2003)(2004)(2005)(2006)(2007)(2008). Their length varied between 20.8 and 75.4 cm (mean ± SD = 38.3 ± 7.94). Female garfish were dominant in larger length groups being most apparent during the resting phase of sexual cycle and in the peak of the spawning period, occurring in April and May. The sexual ratio of all specimens was m/f = 0.98. Males were prevalent in March-at the beginning of the highest spawning activities. Fifty percentage of the garfish population sexually matured at 28.5 cm of total length. Males and females reached their sexual maturity at 28.0 and 31.5 cm of total length, respectively. Spawning began in January peaking during March to May. According to their maturity stages, gonad weight and the gonadosomatic index, males began to spawn one month earlier (April) than females (May). The mean batch fecundity of garfish was 1,242.46 ± 843.64 of matured oocytes per ovary. Matured oocyte diameters ranged from 1.223 to 4.283 mm with the mean value of 2.269 ± 0.332 mm.

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Thermal dynamics of ovarian maturation in Atlantic cod (Gadus morhua)

Cited by 106 publications

References 69 publications

Frequent skipped spawning in the world’s largest cod population

Frequent skipped spawning in the world’s largest cod population

Extent and ecological importance of escape through spawning in sea-cages for Atlantic cod

The reproductive cycle, size at maturity and fecundity of garfish (Belone belone, L. 1761) in the eastern Adriatic Sea

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