scholarly journals Water temperature and timing of capelin spawning determine seabird diets

2012 ◽  
Vol 69 (7) ◽  
pp. 1234-1241 ◽  
Author(s):  
Gail K. Davoren ◽  
Paulette Penton ◽  
Chantelle Burke ◽  
William A. Montevecchi

Abstract Davoren, G. K., Penton, P., Burke, C., and Montevecchi, W. A. 2012. Water temperature and timing of capelin spawning determine seabird diets. – ICES Journal of Marine Science, 69: . The capelin (Mallotus villosus) is the focal forage fish in many northern marine ecosystems. Its capacity to respond to changes in ocean climate is explored and the usefulness of seabird diets as indicators evaluated by integrating the timing of capelin spawning and temperature (0–150 m) during gonadal development (February–June) with colony-based measures of prey deliveries to chicks of common murres (Uria aalge) and northern gannets (Morus bassanus) on the east coast of Newfoundland during the years 1991–1993 and 2003–2010. Great variation was observed in the timing of spawning, with similar annual trends in different regions of coastal Newfoundland. Spawning was later in years of colder-than-average temperature, although the importance of other variables (e.g. fish size) could not be ruled out. The relationship between temperature during gonadal development and timing of spawning was weak at demersal spawning sites, suggesting that timing may be regulated by other factors (e.g. temperature at spawning sites). When spawning was early in warmer years relative to chick-rearing, common murres delivered a lower percentage of energy-rich gravid capelin to their chicks and northern gannets delivered a lower percentage of capelin. Integrating multiple data sources will be important to monitor marine ecosystem health as ocean climate changes.

2020 ◽  
Vol 637 ◽  
pp. 117-140 ◽  
Author(s):  
DW McGowan ◽  
ED Goldstein ◽  
ML Arimitsu ◽  
AL Deary ◽  
O Ormseth ◽  
...  

Pacific capelin Mallotus catervarius are planktivorous small pelagic fish that serve an intermediate trophic role in marine food webs. Due to the lack of a directed fishery or monitoring of capelin in the Northeast Pacific, limited information is available on their distribution and abundance, and how spatio-temporal fluctuations in capelin density affect their availability as prey. To provide information on life history, spatial patterns, and population dynamics of capelin in the Gulf of Alaska (GOA), we modeled distributions of spawning habitat and larval dispersal, and synthesized spatially indexed data from multiple independent sources from 1996 to 2016. Potential capelin spawning areas were broadly distributed across the GOA. Models of larval drift show the GOA’s advective circulation patterns disperse capelin larvae over the continental shelf and upper slope, indicating potential connections between spawning areas and observed offshore distributions that are influenced by the location and timing of spawning. Spatial overlap in composite distributions of larval and age-1+ fish was used to identify core areas where capelin consistently occur and concentrate. Capelin primarily occupy shelf waters near the Kodiak Archipelago, and are patchily distributed across the GOA shelf and inshore waters. Interannual variations in abundance along with spatio-temporal differences in density indicate that the availability of capelin to predators and monitoring surveys is highly variable in the GOA. We demonstrate that the limitations of individual data series can be compensated for by integrating multiple data sources to monitor fluctuations in distributions and abundance trends of an ecologically important species across a large marine ecosystem.


2021 ◽  
pp. 102614
Author(s):  
Florian Berg ◽  
Samina Shirajee ◽  
Arild Folkvord ◽  
Jane Aanestad Godiksen ◽  
Georg Skaret ◽  
...  

2014 ◽  
Vol 92 (5) ◽  
pp. 377-382 ◽  
Author(s):  
Paulette M. Penton ◽  
Craig T. McFarlane ◽  
Erin K. Spice ◽  
Margaret F. Docker ◽  
Gail K. Davoren

Capelin (Mallotus villosus (Müller, 1776)), a focal forage fish in the north Atlantic, spawn on both beach and demersal (deep-water) sites throughout their circumpolar distribution. Although these habitats rarely occur in close proximity, demersal spawning sites within 4 km of beach spawning sites (subtidal) have recently been discovered in two coastal embayments in Newfoundland, Canada. The physical environment differs considerably between beach and subtidal spawning sites, creating the potential for local adaptation and genetic divergence of capelin from the two habitats, but this has never been investigated on a fine spatial scale. We use eight microsatellite loci to test for genetic divergence between capelin spawning at beach and subtidal sites within these two coastal regions in Newfoundland. We found no genetic differentiation between fish spawning at beach and subtidal sites or between the two regions. The results from this fine-scale study are in agreement with the lack of habitat-based structure reported in other studies examining beach and demersal sites separated by a larger geographic area. We suggest that instead of showing site fidelity and local adaptation, the facultative use of alternate spawning habitats may be a more successful strategy in an unpredictable environment.


2020 ◽  
Vol 19 (1) ◽  
pp. 33-43
Author(s):  
Sidonio Machaieie ◽  
Isabel M. Silva

Seasonal aggregations at specific sites are common among some fish species. Experienced fishermen know where and when these aggregations happen, often targeting these spawning sites to increase their catch. This strategy can further contribute to endangering the survival of these species, especially for those already threatened by other forms of pressure. This study contributes knowledge to the spawning aggregation of fish in the north of Mozambique following survey work conducted around Cabo Delgado Province in six coastal villages in 2016, 2017 and 2018. The objectives of the study were 1) to identify the species and sites of spawning aggregation and 2) to determine the timing of spawning aggregations. Data collection consisted of interviews targeting the most experienced fishermen to obtain information on these subjects. The results indicate that out of 124 fishermen interviewed, 59% had knowledge of spawning aggregations. The information collected from fisher interviews revealed that there are at least six spawning locations and at least eight species aggregate to spawn (Leptoscarus vaigensis, Lethrinus harak, Lethrinus nebulosus, Lethrinus obsoletus, Lethrinus olivaceus, Plectorhinchus gaterinus, Plectorhinchus schotaf, Siganus sutor). Only Siganus sutor was reported to spawn in at least one of the fishing areas used by every village. The timing of spawning aggregations most reported by fishermen was during the Kusi (South) monsoon period.


2005 ◽  
Vol 62 (12) ◽  
pp. 2841-2853 ◽  
Author(s):  
Douglas F Bertram ◽  
Anne Harfenist ◽  
Barry D Smith

We report on the survival of populations of Cassin's Auklet (Ptychoramphus aleuticus) that breed on two oceanic colonies in British Columbia: Triangle Island, near the northern end of the California Current Ecosystem, and Frederick Island to the north in the Alaska Current Ecosystem. We captured and banded birds at both colonies from 1994 to 2000 and analyzed the recovery data with the computer program MARK. Average local adult annual survival (± standard error) was significantly lower (p = 0.0001) on Triangle Island (0.71 ± 0.02) than that on Frederick Island (0.80 ± 0.02), likely a result of poor production in the California Current Ecosystem during the 1990s. Coincident with a strong El Niño event, survival in 1997-1998 fell in unison to the lowest values observed for both colonies (to 0.54 ± 0.05 and 0.64 ± 0.04, respectively, for adults). A common winter environment in the California Current Ecosystem could explain the unified mortality response of both British Columbia populations to an exceptionally poor food period. The seabird colonies in this study occupy key positions in relation to major oceanographic domains and hence provide unique platforms for investigations of marine ecosystem response to ocean climate variability in the Northeast Pacific Ocean.


Polar Biology ◽  
1996 ◽  
Vol 16 (3) ◽  
pp. 201-207 ◽  
Author(s):  
Thomas W. Therriault ◽  
David C. Schneider ◽  
David A. Methven

1987 ◽  
Vol 65 (7) ◽  
pp. 1638-1649 ◽  
Author(s):  
T. R. Birkhead ◽  
D. N. Nettleship

A simultaneous comparison of the foods of Common Murre, Uria aalge, and Thick-billed Murre, Uria lomvia, chicks at the same location showed that the species composition of fish fed to chicks of the two murre species differed significantly. In both years of the study, Common Murre chicks were fed predominantly capelin, Mallotus villosus (78–80% by weight), whereas Thick-billed Murre chicks were fed mainly daubed shanny, Lumpenus maculatus (61–70% by weight). Thick-billed Murres tended to feed their chicks more frequently than Common Murres, probably because in both years the mean caloric value of their prey was lower than that of the Common Murre's. No other statistically significant interspecific differences were consistent between years. Prey lengths and weights overlapped considerably between the murre species, and the caloric intake of chicks showed no consistent interspecific difference. Marked interyear differences in feeding rate, prey size, and caloric intake occurred in both species. In 1982 ice breakup was late, and the murres' breeding seasons were delayed; this appeared to result in poor synchronization between the temporal pattern of food availability and the timing of each species' chick-rearing period, and the caloric intakes of chicks of both species were lower in that year than in 1983.


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