Effects of fish size on spawning time in Norwegian spring-spawning herring

Abstract

During October-January in a northern Norwegian fjord system and in February-March at the main western Norway spawning grounds, an index I G of gonad weight of spring-spawning herring Clupea harengus in percentage of expected gonad weight at full maturity for a given total length L T , tended to increase with L T in the range 27-31 cm as the proportion of recruit spawners decreased. Insignificant differences in I G were found between L T groups in the range 32-37 cm (repeat spawners). This is contrary to that suggested in other studies and signifies that generally the stock spawns in only two waves, repeat spawners first and the recruit spawners second. I G also increased with somatic and total condition factor, which signifies that spawning time may be influenced by summer feeding conditions.2000 The Fisheries Society of the British Isles

Effect of size on spawning time in the lesser sandeel Ammodytes marinus

“…The positive effect of L T on oocyte diameter in December indicates an earlier onset of spawning in large female A. marinus . A similar length effect on relative ovary size has been linked to two waves of spawning in Norwegian spring spawning C. harengus (Slotte et al, ). Although little is known about the precise timing of spawning in A. marinus , the present study suggests that asynchrony in the onset of spawning could extend the period over which individuals spawn within a population.…”

“…The length effect on oocyte development probably reflects differences in energy stores as larger A. marinus attain a higher condition by the onset of over‐wintering (Rindorf et al, ). The early onset of spawning has also been found to be related to somatic condition in C. harengus , another capital breeder (Slotte et al, ). Indeed, some of the most extensive evidence of size‐dependent spawning time has been found in C. harengus (Ware & Tanasichuk, ) and it is thought that this trend in wild fish is caused by fish of different sizes experiencing different environmental conditions, such as temperature.…”

“…A few species, however, exhibit short, highly synchronized spawning seasons and this is often linked to high intra‐season variation in selection on progeny birth date (Wright & Trippel, ). In some cases, larger, older or experienced adults have been found to spawn before young, first‐time spawners (Slotte et al, ; Wright & Gibb, ). This may relate to some ontogenetic predisposition to alter the onset of spawning times or just reflect the tendency for high conditioned fishes to spawn earlier (Trippel et al, ).…”

Ovary development in Greenland halibut Reinhardtius hippoglossoides in west Greenland waters

“…One hypothesis is that larger Greenland halibut females start maturing earlier in the year compared to smaller females. This is for instance seen in herring Clupea harengus L. and several other fish species (Slotte et al ., 2000). A study on Greenland halibut in the Barents Sea showed that the large fast growing individuals started the spawning migration earlier than smaller ones (Albert, 2003).…”

Onset of maturity and cohort composition at spawning of Baltic sprat Sprattus sprattus on the basis of otolith macrostructure analysis

“…This migration has been suggested to be size‐dependent with larger fishes flooding into the spawning grounds first and spawning earlier compared to smaller specimens (Dragesund et al ., 1980; Hay, 1985; Dawson, 1986; Lambert & Messieh, 1989). Moreover, to be age‐dependent with younger fishes spawning first ( C. harengus ; Lambert, 1987), and finally in some cases repeat spawners have been found to spawn first and recruit spawners later (Slotte et al ., 2000).…”