Norwegian Spring-spawning Herring Clupea Harengus Research Articles

Long-term changes in the total egg production of Norwegian spring-spawning herring Clupea harengus (L.)—Implications of variations in population structure and condition factor

The reproductive potential of Norwegian spring-spawning herring ( Clupea harengus) was estimated in terms of total egg production (TEP) for the period 1935–2005, using a model where spawning stock numbers (SSN)-, weight- and length-at-age were combined with fecundity–weight relationships. In general, the modelled TEP was closely related to SSN. However, larger positive and negative deviations from this relationship were found in periods with high SSN in combination with increasing proportions of either recruit or repeat spawners and condition factor ( K) below 0.73 or above 0.8. When relating the current estimated TEP to similar type of figures based on earlier data (including fecundity observations in 1951–1983), deviations were less pronounced, but they still tended to occur in periods of high SSN. These results suggest that at stable high stock levels, the population structure and its condition in terms of K, can have implications for the reproductive output. Hence, quantification of the reproductive potential as TEP has the potential to strengthen the stock–recruitment models, because it captures both the stock population structure and reproductive dynamics.

Food web interactions in the southwestern Barents Sea: black-legged kittiwakes Rissa tridactyla respond negatively to an increase in herring Clupea harengus

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 349:269-276 (2007) - DOI: https://doi.org/10.3354/meps07116 Food web interactions in the southwestern Barents Sea: black-legged kittiwakes Rissa tridactyla respond negatively to an increase in herring Clupea harengus Robert T. Barrett* Zoology Department, Tromsø University Museum, 9037 Tromsø, Norway *Email: robb@tmu.uit.no ABSTRACT: Since 1980 the stock of Norwegian spring-spawning herring Clupea harengus has increased 10-fold to >5 × 106 t. This increase has probably played a vital role in repeated collapses in the capelin Mallotus villosus stock in the Barents Sea since the mid-1980s. After several decades of increase during a period of high capelin abundance in the Barents Sea, the population of black-legged kittiwakes Rissa tridactyla breeding in northern Norway started to decline in the early 1980s, reaching rates of –8% yr–1 since 1995. Earlier studies in the southwestern Barents Sea suggested that the black-legged kittiwakes in the region were dependent on capelin as prey for successful breeding. This study further documents a positive relationship between diet composition and fish abundance, and the negative effect that a switch to feeding on herring in the absence of capelin has had on chick provisioning and possibly fledging success. KEY WORDS: Seabirds · Black-legged kittiwake · Diet · Breeding success · Food web interactions Full text in pdf format PreviousNextCite this article as: Barrett RT (2007) Food web interactions in the southwestern Barents Sea: black-legged kittiwakes Rissa tridactyla respond negatively to an increase in herring Clupea harengus. Mar Ecol Prog Ser 349:269-276. https://doi.org/10.3354/meps07116 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 349. Online publication date: November 08, 2007 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2007 Inter-Research.

Fish and oil in the Lofoten–Barents Sea system: synoptic review of the effect of oil spills on fish populations

The Lofoten-Barents Sea area, which contains some of the most valuable fish stocks of the Atlantic Ocean, is being considered for offshore oil production. We review the effects of a hypothetical oil spill on fishes in this area, with a focus on effects on the egg and larval stage of the 3 dominating fish stocks: NE Arctic cod Gadus morhua, Barents Sea capelin Mallotus villosus, and Norwegian spring-spawning herring Clupea harengus. In particular, we emphasise that the long- term population impact of an oil spill depends on ecological and oceanographic factors, some of which have been poorly explored. Among these are (1) effects of the physical state of the ocean, espe- cially mesoscale circulation features, on the advection of oil and fish larvae, (2) effects of the spatial distribution of spawners, (3) effects of harvesting on stock structure and length of the spawning sea- son, (4) effects of natural mortality and species interactions subsequent to an oil spill, and (5) chronic sublethal effects from persistent oil residues.

Maturity changes in Norwegian spring-spawning herring Clupea harengus: compensatory or evolutionary responses?

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 272:245-256 (2004) - doi:10.3354/meps272245 Maturity changes in Norwegian spring-spawning herring Clupea harengus: compensatory or evolutionary responses? Georg H. Engelhard1,2,*, Mikko Heino1,3 1Institute of Marine Research, PO Box 1870 Nordnes, 5817 Bergen, Norway 2CEFAS Lowestoft Laboratory, Pakefield Road, Lowestoft NR33 0HT, UK 3Adaptive Dynamics Network, International Institute for Applied Systems Analysis, 2361 Laxenburg, Austria *Email: g.engelhard@cefas.co.uk ABSTRACT: The stock of Norwegian spring-spawning herring Clupea harengus collapsed to a state of commercial extinction in the 1960s, probably due to both overexploitation and unfavourable climatic conditions. Since the 1980s, the stock has fully recovered. Following the collapse, the fish matured at much earlier ages and somewhat larger sizes than previously. Currently, age and size at 50% maturity have only to some extent returned to pre-collapse levels. Two non-exclusive hypotheses that may account for the maturity changes are (1) the Œcompensatory response¹ hypothesis, predicting that reduced stock size resulting from exploitation leads to faster growth and hence earlier maturity as a phenotypically plastic response to environmental change; and (2) the Œevolutionary response¹ hypothesis, predicting that intensive exploitation causes selection for early maturation, since few late-maturing phenotypes survive until first spawning. Trends in length-at-age suggest a strong compensatory response, but leave the possibility of evolutionary change unaddressed. In order to disentangle phenotypic and possible genetic changes in maturation, we examined the reaction norm for age and size at maturation to see if any changes had occurred. This reaction norm describes the probabilities of maturing at each relevant age and size. We found small but statistically significant changes in maturation reaction norms; these changes were restricted to 2 out of 6 of the maturation ages. This confirms that growth-related phenotypic plasticity has largely been responsible for the documented changes in maturity, and suggests at most a weak evolutionary response. This is in line with theoretical expectations from the dominating fishing pattern, where pure schools of only mature or only early immature fish were targeted, rather than a fishery on both immature and mature fish simultaneously, as has been the case in stocks of cod Gadus morhua and plaice Pleuronectes platessa, where significant evolutionary responses have been found. KEY WORDS: Fisheries-induced change · Evolution · Phenotypic plasticity · Reaction norm · Maturation · Growth rates Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 272. Online publication date: May 19, 2004 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2004 Inter-Research.

Await in the pelagic: dynamic trade-off between reproduction and survival within a herring school splitting vertically during spawning

Spatio-temporal aspects of spawning behaviour were investigated in a single school of Norwegian spring-spawning herring Clupea harengus, and are explained by changes in the relative importance of reproduction, predation and feeding during spawning. Horizontal area, vertical exten- sion, school shape and relative density were quantified using sonar and echosounder, and related to gonad maturation stage and stomach fullness recorded from gillnet samples. The majority of the her- ring completed spawning within 3 d. During this period, the herring were feeding and predatory fish were present in the area. An extended cylindrical school shape prior to spawning indicated that indi- vidual herring within the school had different depth preferences, with ripe individuals descending towards the spawning substrate on the bottom while immature individuals preferred the pelagic environment for safety and feeding. As the majority of the fish matured, the school segregated verti- cally into a pelagic component that contracted to a tight ball and a demersal component that spread out in a flat layer on the bottom. Post-spawners seemed to return to the pelagic school. After spawn- ing, the 2 components rejoined each other and formed a loose flake (i.e. loose, uneven layer) at the surface. Schooling fish have traditionally been considered to make 1 of 3 behavioural decisions: to stay, join or leave a school. Waiting without losing contact with the rest of the school, 'await', is sug- gested as a fourth option.

State-dependent spawning migration in Norwegian spring-spawning herring

Norwegian spring-spawning herring Clupea harengus winter in fjords of northern Norway, whereas the subsequent spawning occurs at various locations along the coast with a main bulk off the south-western coast. The distance of the southward spawning migration tends to increase with the length and condition of the fish. The costs and benefits of the southward migration were modelled in terms of fitness (number of surviving offspring). The model assumes that larvae have increasing growth and survival rates further south as they pass through warmer water during the northward drift in the coastal current. In agreement with the observed spawning distribution, optimal spawning grounds were predicted off the southwestern coast and farther south with increasing fish length and condition. The present study suggests that homing is not a successful strategy for these herring, and instead the selection of spawning grounds depends on individual internal state (length, condition), the cost of migration and the probability of larval survival.