Summer Diet of the Harbour Porpoise (Phocoena phocoena) in the Estuary and the Northern Gulf of St. Lawrence

1994 ◽  
Vol 51 (1) ◽  
pp. 172-178 ◽  
Author(s):  
Pierre-Michel Fontaine ◽  
Mike O. Hammill ◽  
Cyrille Barrette ◽  
Michael C. Kingsley
Keyword(s):  
Stomach Contents ◽  
Harbour Porpoise ◽  
Clupea Harengus ◽  
Frequency Of Occurrence ◽  
Atlantic Herring ◽  
Phocoena Phocoena ◽  
Mallotus Villosus ◽  
Important Species ◽  
Caloric Value ◽  
Capelin Mallotus Villosus

Stomach contents (n = 138) were examined in harbour porpoise (Phocoena phocoena) caught incidently by commercial fishermen in the estuary and the Gulf of St. Lawrence; 111 stomachs contained food. A total of 4423 otoliths and 11 upper beaks were collected belonging to nine species of fishes and one species of squid. Capelin (Mallotus villosus), Atlantic herring (Clupea harengus), and redfish (Sebastes marinus) were the three most important species in the diet by frequency of occurrence (83, 8, and 4.5%, respectively) and percent occurrence in the stomachs (52, 49, and 8.5%). Capelin and herring also made the greatest mass and caloric contribution to the diet of porpoise (>80%). The estimated mean mass and caloric value of the stomach contents of a nonlactating adults were 958 g and 7007 kJ, respectively.

Interactions multispécifiques: répartition spatio-temporelle des larves de capelan (Mallotus villosus), d'éperlan (Osmerus mordax) et de hareng de l'Atlantique (Clupea harengus harengus) an sein de la communauté planctonique de l'estuaire moyen du Saint-Laurent

1982 ◽  
Vol 39 (8) ◽  
pp. 1164-1174 ◽  
Author(s):  
R. Courtois ◽  
M. Simoneau ◽  
J. J. Dodson
Keyword(s):  
Fish Larvae ◽  
Clupea Harengus ◽  
Temporal Organization ◽  
Physical Factors ◽  
Osmerus Mordax ◽  
Mallotus Villosus ◽  
Saint Lawrence River ◽  
Capelin Mallotus Villosus ◽  
Clupea Harengus Harengus ◽  
Species Specific

The study of the spatial and temporal organization of the planktonic community of the middle estuary of the Saint Lawrence River revealed that fish larvae were distributed in such a way as to minimize interactions between species. Smelt (Osmerus mordax) larvae were distributed upstream whereas capelin (Mallotus villosus) and Atlantic herring (Clupea harengus harengus) larvae were found downstream in June 1979. Capelin larvae were more abundant at the surface (0–20 m) whereas herring larvae were concentrated in deeper waters (20–60 m). The ecological separation observed was maintained by multiple physical factors and appeared to be the consequence of species-specific reproductive strategies. The abundance of chaetognaths, euphausiids, and amphipods in deeper waters suggests that these forms could be important predators of fish larvae. Herring larvae may be particularly vulnerable because of their distribution in deep water. Capelin larvae which are very abundant in June could also be vulnerable to predation during the diurnal migrations of the macroplankton. Smelt larvae appear to be little affected by predation from these forms as a result of their distribution in fresher waters.

Mitigation of harbour porpoise (Phocoena phocoena) by-catch in the gillnet fishery in the lower Bay of Fundy

1999 ◽  
Vol 56 (1) ◽  
pp. 113-123 ◽  
Author(s):  
Edward A Trippel ◽  
Michael B Strong ◽  
John M Terhune ◽  
Jeremy D Conway
Keyword(s):  
Gadus Morhua ◽  
Atlantic Cod ◽  
Field Testing ◽  
Harbour Porpoise ◽  
Clupea Harengus ◽  
Bay Of Fundy ◽  
Phocoena Phocoena ◽  
By Catch ◽  
Catch Rates ◽  
Wind Sea

Demersal gill nets equipped with acoustic alarms reduced harbour porpoise (Phocoena phocoena) by-catch rates by 77% over those without alarms in the Swallowtail area of the lower Bay of Fundy during field testing in August 1996 (68% reduction) and 1997 (85% reduction) (both years combined, three harbour porpoises in 249 alarmed nets versus 14 harbour porpoises in 267 nonalarmed nets). The alarms spaced 100 m apart along the net floatline produced a 0.3-s pulse at 10-12 kHz every 4 s at a level of 133-145 dB re 1 µPa at 1 m. In conditions of no rain and low wind (Sea State 0-2) the alarms were presumed to be clearly audible to harbour porpoises at ranges of 0.1-0.6 km. Catch rates of Atlantic herring (Clupea harengus), Atlantic cod (Gadus morhua), and pollock (Pollachius virens) were not significantly different in alarmed and nonalarmed nets (except in one season when pollock were caught in lower numbers in alarmed nets). Harbour porpoise by-catch and herring movements may be linked. During years of low herring abundance, we also observed low harbour porpoise entanglement rates.

Effects of predation from juvenile herring (Clupea harengus) on mortality rates of capelin (Mallotus villosus) larvae

2009 ◽  
Vol 66 (10) ◽  
pp. 1693-1706 ◽  
Author(s):  
Elvar H. Hallfredsson ◽  
Torstein Pedersen
Keyword(s):  
Barents Sea ◽  
Fish Larvae ◽  
Mortality Rates ◽  
Clupea Harengus ◽  
Mallotus Villosus ◽  
Rate Estimate ◽  
Predator Prey ◽  
The Barents Sea ◽  
Capelin Mallotus Villosus ◽  
Larvae Density

Predation has been suggested as a cause of substantial mortality of fish larvae to the degree that it might influence recruitment. This field-based study concludes that juvenile herring ( Clupea harengus ) as small pelagic predator can significantly affect mortality rates of the planktonic larvae of capelin ( Mallotus villosus ) in the Barents Sea. Surveys were carried out in the summers of 2001 and 2003. In 2001, juvenile herring were widely distributed and overlapped with capelin larvae over a wide area, whereas in 2003, the herring were more aggregated. The study focused on predation in the areas of predator–prey overlap. Capelin larvae were observed in the herring stomachs at 11 of 24 stations and at 8 of 16 stations where herring were caught in 2001 and 2003, respectively. At those stations, an estimated 7.3% and 9.9% of the capelin larvae were eaten by herring per day in 2001 and 2003, respectively. Statistical models revealed that density of capelin larvae and copepods and occurrence of euphausiids in the stomachs affected the number of capelin larvae per predator stomach. A simplified model with only capelin larvae density as predictor was converted to a functional response relationship using an experimentally derived digestion rate estimate for capelin larvae in herring stomachs.

Effects of predation from pelagic 0-group cod (Gadus morhua) on mortality rates of capelin (Mallotus villosus) larvae in the Barents Sea

2007 ◽  
Vol 64 (12) ◽  
pp. 1710-1722 ◽  
Author(s):  
Elvar H Hallfredsson ◽  
Torstein Pedersen
Keyword(s):  
Mortality Rate ◽  
Stomach Content ◽  
Gadus Morhua ◽  
Barents Sea ◽  
Stomach Contents ◽  
Mortality Rates ◽  
Mallotus Villosus ◽  
The Barents Sea ◽  
Predation Mortality ◽  
Capelin Mallotus Villosus

Surveys were carried out in 2002 and 2003 to test whether predation from pelagic 0-group cod (Gadus morhua) juveniles affects mortality rates of Barents Sea capelin (Mallotus villosus) larvae. In 2002, capelin larvae were observed in 17% of the cod stomachs and predation was observed at 19 of 50 stations. In 2003, capelin larvae were observed in 8% of the cod stomachs and predation was observed at 19 of 37 stations. The stomach contents and zooplankton samples were dominated by copepods and krill. The number of capelin larvae in cod stomachs increased with increasing capelin larvae abundance and cod length and decreased with increasing stomach content of copepods and prey abundance of krill. The time when capelin larvae could be recognised after ingestion in the cod stomachs was estimated experimentally and depended on predator and prey lengths. The estimated overall predation mortality rate from juvenile cod on capelin larvae was about 1.5% per day for both years and can potentially have a significant effect on the survival of capelin larvae, depending on the overlap in the different years.

Consumption of euphausiids by harbour porpoise (Phocoena phocoena) calves in the Bay of Fundy

1992 ◽  
Vol 70 (8) ◽  
pp. 1629-1632 ◽  
Author(s):  
Richard J. Smith ◽  
Andrew J. Read
Keyword(s):  
Fish Species ◽  
Prey Item ◽  
Stomach Contents ◽  
Harbour Porpoise ◽  
Bay Of Fundy ◽  
Phocoena Phocoena ◽  
Gill Nets ◽  
Meganyctiphanes Norvegica

We compared the contents of 31 stomachs of harbour porpoise calves killed in commercial gill nets in the Bay of Fundy between July and September, 1985–1991, with the stomach contents from 149 adult animals obtained from the same source between July and September, 1988–1991. The calves' most common prey item was the euphausiid Meganyctiphanes norvegica, found in 15 stomachs, whereas the adults fed primarily on clupeid and gadid fishes. Euphausiids were also found in the stomachs of several of these fish species, and we suggest that porpoise calves take euphausiids while their mothers are feeding on other euphausiid predators.

scholarly journals Trophic interactions affecting a key ecosystem component: a multistage analysis of the recruitment of the Barents Sea capelin (Mallotus villosus)

2010 ◽  
Vol 67 (9) ◽  
pp. 1363-1375 ◽  
Author(s):  
Dag Øystein Hjermann ◽  
Bjarte Bogstad ◽  
Gjert Endre Dingsør ◽  
Harald Gjøsæter ◽  
Geir Ottersen ◽  
...  
Keyword(s):  
Trophic Interactions ◽  
Gadus Morhua ◽  
Barents Sea ◽  
Clupea Harengus ◽  
Mallotus Villosus ◽  
The Barents Sea ◽  
Key Species ◽  
Capelin Mallotus Villosus ◽  
Ecosystem Component ◽  
Recruitment Stages

The Barents Sea stock of capelin ( Mallotus villosus ) has suffered three major collapses (>90% reduction) since 1985 due to recruitment failures. As capelin is a key species in the area, these population collapses have had major ecosystem consequences. By analysing data on spawner biomass and three recruitment stages (larvae, 0-group, and 1-year-olds), we suggest that much of the recruitment failures are caused by predation from herring ( Clupea harengus ) and 0-group and adult Northeast Arctic cod ( Gadus morhua ). Recruitment is furthermore positively correlated with sea temperatures in winter and spring. Harvesting of maturing capelin on their way to the spawning grounds reduced the abundance of larvae significantly, but this reduction to a large extent is compensated for later in life, as mortality is strongly density-dependent between the larval stage and age 1. Altogether, our study indicates a very high importance of trophic interactions, consistent with similar findings in other high-latitude marine ecosystems.

scholarly journals Sources of variation in stomach contents of predators of Atlantic herring in the Northwest Atlantic during 1973–2014

2018 ◽  
Vol 75 (4) ◽  
pp. 1439-1450 ◽  
Author(s):  
Jonathan J Deroba
Keyword(s):  
Stomach Contents ◽  
Clupea Harengus ◽  
Spatial And Temporal Variation ◽  
Atlantic Herring ◽  
Predator Species ◽  
Stock Assessments ◽  
Generalized Additive Mixed Models ◽  
Additive Mixed Models ◽  
Sources Of Variation ◽  
Biased Estimates

AbstractSpatial and temporal variation in stomach-contents data is often unquantified or combined in such a way (e.g. averaged among years) that true signal in diets may be lost. Using a delta approach, this paper fits generalized additive mixed models (GAMMs) to the amount of Atlantic herring (Clupea harengus) identified in predator stomachs using only data from stomachs in which herring occurred, and to the probability that a stomach contained herring. Both the amount of herring in stomachs and the probability of a stomach containing herring varied seasonally, spatially, and among years. Of the random effects in each GAMM, the effect of predator species had the largest variance. An index of herring abundance derived from the stomach-contents data was generally consistent with recent herring stock assessments. The temporal and spatial variation in the stomach-contents data suggested that the effect of averaging or combining stomach-contents data among years, seasons, or areas may lead to falsely precise or biased estimates from multispecies assessments or in estimates of consumption, and may restrain the relevance of static foodweb models.

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