Regional variation in maturation of sandeels in the North Sea

Boulcott, Philip; Wright, Peter J.; Gibb, Fiona M.; Jensen, Henrik; Gibb, Iain M.

doi:10.1093/icesjms/fsl033

Cited by 51 publications

(60 citation statements)

References 29 publications

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“…Significant regional differences in length-at-age and annual growth rates have previously been found, with sandeels in the Firth of Forth aggregation being smaller and having slower growth rates than elsewhere (Wanless et al 2004, Boulcott et al 2007. Results presented here indicate that this regional disparity may have become even more marked in recent years.…”

Section: Discussionsupporting

confidence: 52%

“…Moreover, as fecundity also scales to size, smaller length-at-age is likely to be associated with reduced fecundity-at-age (Macer 1966, Gauld & Hutcheon 1990). This in turn has consequences for the reproductive potential of the Firth of Forth aggregation, tending to make it more vulnerable to collapse through recruitment overfishing and possibly less able to support a level of fishing mortality as high as elsewhere in the North Sea (Boulcott et al 2007). Thus evidence of a continued and possibly accelerating decline in length-at-age of sandeels in the Firth of Forth is of major relevance to decisions regarding the re-opening of this region to commercial fishing.…”

Section: Discussionmentioning

confidence: 99%

“…Sandeel larvae were extracted from archived CPR samples collected between January and July from 1973 to 2006 within an area approximately centred on the seabird colony on the Isle of May (56°11' N, 2°33' W) and the Wee Bankie/Marr Bank sandeel aggregation (Pedersen et al 1999, Boulcott et al 2007, and extending from 54 to 59°N, and from 2°W to 2°E. 0-group sandeels were collected from chick-feeding puffins on the Isle of May between late May and July each year from 1973 to 2006.…”

Section: Methodsmentioning

confidence: 99%

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Mechanisms of long-term decline in size of lesser sandeels in the North Sea explored using a growth and phenology model

Frederiksen¹,

Elston²,

Edwards³

et al. 2011

Mar. Ecol. Prog. Ser.

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The lesser sandeel Ammodytes marinus is a key species in the North Sea ecosystem, transferring energy from planktonic producers to top predators. Previous studies have shown a longterm decline in the size of 0-group sandeels in the western North Sea, but they were unable to pinpoint the mechanism (later hatching, slower growth or changes in size-dependent mortality) or cause. To investigate the first 2 possibilities we combined 2 independent time series of sandeel size, namely data from chick-feeding Atlantic puffins Fratercula arctica and from the Continuous Plankton Recorder (CPR), in a novel statistical model implemented using Markov Chain Monte Carlo (MCMC). The model estimated annual mean length on 1 July, as well as hatching date and growth rate for sandeels from 1973 to 2006. Mean length-at-date declined by 22% over this period, corresponding to a 60% decrease in energy content, with a sharper decline since 2002. Up to the mid-1990s, the decline was associated with a trend towards later hatching. Subsequently, hatching became earlier again, and the continued trend towards smaller size appears to have been driven by lower growth rates, particularly in the most recent years, although we could not rule out changes in size-dependent mortality. Our findings point to major changes in key aspects of sandeel life history, which we consider are most likely due to direct and indirect temperature-related changes over a range of biotic factors, including the seasonal distribution of copepods and intra-and inter-specific competition with planktivorous fish. The results have implications both for the many predators of sandeels and for age and size of maturation in this aggregation of North Sea sandeels. KEY WORDS: Ammodytes marinus · Growth model · MCMC · North Sea · Phenology · SandeelResale or republication not permitted without written consent of the publisher Mar Ecol Prog Ser 432: 137-147, 2011 138 dynamics and to impact higher trophic levels, and indeed have already been linked with fluctuations in both commercially exploited fish stocks , Castonguay et al. 2008 and reproductive performance of land-based predators (Frederiksen et al. 2006, Sydeman et al. 2006.The lesser sandeel Ammodytes marinus (hereinafter sandeel) is a key species in the ecology of the North Sea and other parts of the NE Atlantic (Daan et al. 1990). It is generally the most abundant small planktivorous fish, and provides a critical trophic link between secondary producers (zooplankton, particularly calanoid copepods) and a wide variety of top predators, including larger fish, marine mammals and seabirds. Several studies have highlighted the critical importance of the availability and quality of sandeels for successful reproduction of North Sea seabirds (Monaghan 1992, Rindorf et al. 2000, Wanless et al. 2005. Sandeels are also the target of a major industrial fishery for fishmeal and fish oil (Furness 2002). However, evidence from several sources has indicated that conditions for sandeels in the North Sea are less favourable than...

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Section: Discussionsupporting

confidence: 52%

Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Mechanisms of long-term decline in size of lesser sandeels in the North Sea explored using a growth and phenology model

Frederiksen¹,

Elston²,

Edwards³

et al. 2011

Mar. Ecol. Prog. Ser.

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“…Pacific Sand Lances in this region are known to spawn between December and February in intertidal habitats (Penttila 1995), and Lesser Sand Eels A. marinus can migrate between deep and nearshore waters as a function of season and life stage (Andriyashev 1954;Gauld 1990); however, the lack of differentiation of the size-classes of fish sampled suggest that the increased abundance in the sediments represents a transition from pelagic foraging to benthic dormancy rather than an influx in the return of spawning adults. Additionally, while Ammoydytes species mature at various ages across their range , and size at maturity is not known for the local population (Selleck et al 2015), maturation does not occur until fish exceed 100 mm in length (Boulcott et al 2007). Despite close examination of more than 1,000 individuals we noted no evidence of sexual maturation.…”

Section: Trends Across the Fall Transitionmentioning

confidence: 99%

Feeding Ecology of Pacific Sand Lance in the San Juan Archipelago

Sisson

Baker

2017

Mar Coast Fish

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Forage fishes such as Pacific Sand Lance Ammodytes personatus are a crucial link between lower and upper elements in marine food webs, as they transfer energy from plankton to higher trophic levels. Despite their importance to marine food webs, little is known about the population structure and feeding ecology of Pacific Sand Lance. In this study, we examined the population density and diet composition of Pacific Sand Lance as well as feeding patterns and movement in response to tidal, diel, and seasonal cycles in a prominent sand wave field in the San Juan Channel, Washington. A generalized linear model was applied to account for the corresponding effects of tidal, diel, and seasonal trends as well as habitat affinity related to substrate type. We showed that fish distributions were predominantly driven by sediment type and that time of day had a significant influence on foraging behavior with distinct crepuscular feeding patterns. Our results also provide evidence for the cessation of feeding over the fall transition and the onset of a winter dormant period, as observed by increased densities of fish within the sand wave field (177%), a marked increase in the number of empty stomachs (511%), and a significant decrease in condition factor. These trends correspond with the expectations that Pacific Sand Lances exhibit a winter dormant phase and burrow in sediments throughout the winter months to conserve energy and reduce predation risk during periods of low productivity. We anticipate our study to be a starting point for understanding the foraging ecology of the Pacific Sand Lance, particularly in the San Juan Archipelago and Salish Sea. The results of this study may improve the understanding of Pacific Sand Lance habitat and availability to pelagic predators, inform fisheries management, and increase the resolution of marine food web models.The transfer of energy between primary and higher trophic levels in marine ecosystems often occurs through a few species of highly abundant, small forage fishes (Cury et al. 2000). As such, forage fishes are a crucial link between lower and upper elements in the food chain as they transfer energy from primary producers (e.g., phytoplankton) and secondary consumers (e.g., zooplankton) to higher trophic levels (e.g., piscivorous fishes, seabirds, and marine mammals) (Robards et al. 1998;Harvey et al. 2010). These fishes may also channel energy flow between various marine habitats, as many forage fish species occupy intertidal and subtidal communities . Variation in the abundance of forage fish populations can significantly impact marine ecosystems (Bargmann 1998). Thus, despite relatively few focused studies on these taxa, planktivorous fishes are an important component driving trophic dynamics in many marine and coastal ecosystems (Pikitch et al. 2012).

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“…Sandeels in this area belong to a separate aggregation showing different dynamics and life history characteristics than in other parts of the North Sea (Pedersen et al 1999, Boulcott et al 2007. Breeding success of blacklegged kittiwakes was depressed during this period at the Isle of May (Frederiksen et al 2004) and other colonies (Frederiksen et al 2007c), while there was no suggestion of negative effects on breeding success or chick condition for four species of diving seabirds (Frederiksen et al 2008b).…”

Section: Depletion Of Food Stocksmentioning

confidence: 99%

Action plan for seabirds in Western-Nordic areas

2010

TemaNord

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Regional variation in maturation of sandeels in the North Sea

Cited by 51 publications

References 29 publications

Mechanisms of long-term decline in size of lesser sandeels in the North Sea explored using a growth and phenology model

Mechanisms of long-term decline in size of lesser sandeels in the North Sea explored using a growth and phenology model

Feeding Ecology of Pacific Sand Lance in the San Juan Archipelago

Action plan for seabirds in Western-Nordic areas

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