Feeding Hotspots and Distribution of Fin and Humpback Whales in the Norwegian Sea From 2013 to 2018.

Fin whales (Balaenoptera physalus) and humpback whales (Megaptera novaeangliae) are commonly found in the Norwegian Sea during the summer months. Records from around 1995 to 2004 show that their distribution patterns were mainly associated with those of macro-zooplankton. More recent studies conducted from 2009 to 2012 demonstrate marked shifts, with fin whale distribution related to pelagic fish distribution, decreasing densities of humpbacks, and increased densities of toothed whales. During the same period, historically large abundances of pelagic planktivorous fish in the Norwegian Sea were reported. The goals of this study were to examine the summer distribution of fin and humpback whales from 2013 to 2018 and to assess the potential association between distribution and environmental impact factors. Results suggest a pronounced northerly shift in distribution for both species, a feeding hotspot for fin whales at the shelf area between Svalbard and Norway, and one near Bear Island for humpback whales. Fin whale distribution was associated with that of blue whiting (Micromesistius poutassou) and capelin (Mallotus villosus), whereas humpback whale distribution was associated with that of euphausiids (Meganyctiphanes norvegica, Thysanoessa longicaudata, and Thysanoessa inermis), capelin, and herring (Clupea harengus). However, a significant negative spatial correlation was found between whale occurrence and the widely expanding population of northeast Atlantic mackerel (Scomber scombrus). The results of this study suggest that the prey composition of fin and humpback whales in recent years contain a large proportion of fish. The apparent northerly shift in the distribution of these whale species is largely determined by the availability of prey, but it likely is also impacted by direct or indirect interspecific interactions, especially with killer whales (Orcinus orca). Such large-scale pronounced changes in distribution seem to confirm a high degree of plasticity in fin and humpback whale feeding in the Norwegian Sea.publishedVersio

Testing of trawl-acoustic stock estimation of spawning capelin 2020

This report describes the second in a series of three trawl-acoustic monitoring surveys of the spawning stock of capelin during the migration to the coast. The survey is a response to a proposal from the industry to evaluate the possibility of using winter monitoring of maturing capelin as an input to the capelin assessment and advice. The timing and geographic coverage of the survey are such that they would be relevant to use for advice given that the output is reliable. Pre-defined areas off the Troms and Finnmark coast were covered using two vessels, Vendla surveying the western part and Eros the eastern part. A stratified random transect design was adopted with two complementary zig-zag grids, the first going in a west-east and the second in an east-west direction over the same strata. The ultimate biomass estimate combines the two coverages, but evaluation about the mobility of the fish can be done by comparing the coverages. The final geographical allocation of survey effort was decided based on information from the scouting vessel Hovden Viking which covered the area a week prior to the main survey. Echo sounders with frequencies from 18-200 kHz were run together with sonars, and target trawls were carried out on significant pelagic aggregations. Capelin abundance was estimated using 38 kHz data. The total biomass of maturing capelin in the coverage area was estimated at 62 298 tons, with a CV of 38%. The 5% lower and 95% upper confidence limits were 26 655 and 104 305 tons, respectively. The result is in accordance with the prediction from the autumn 2019, but the high CV and wide confidence interval show that the survey result is uncertain. The high uncertainty despite the good survey coverage is likely due to the very patchy distribution of the capelin. In addition, in the western coverage area which had most of the capelin recordings, there was a big difference in both estimate and distribution in the return east-west coverage compared to the west-east. This underlines the high mobility of the capelin when it is in this state of migration. The strong dynamic was also evident last year and makes the monitoring of the capelin spawning migration challenging. Mean length of the capelin was 16.2 cm, mean weight 22.3 g, and maturation had progressed further in the western than the eastern area which was the opposite of what was observed last year. Methodological investigations including target strength measurements and testing of the autonomous Sailbuoy were carried out successfully and are described in the report. A thorough evaluation of the survey series and its usefulness as input to the capelin advice will be done after the third survey in this series is completed.Testing of trawl-acoustic stock estimation of spawning capelin 2020publishedVersio

Testing of trawl-acoustic stock estimation of spawning capelin 2021

This report describes the third in a series of trawl-acoustic monitoring surveys of the spawning stock of capelin during the migration to the coast. The survey is a response to a proposal from the industry to evaluate the possibility of using winter monitoring of maturing capelin as an input to the capelin assessment and advice. The timing and geographic coverage of the survey are such that they would be relevant to use for advice given that the output is reliable. Pre-defined areas off the Troms and Finnmark coast were covered using two vessels, Vendla surveying the western part and Eros the eastern part.Testing of trawl-acoustic stock estimation of spawning capelin 2021publishedVersio

Utbredelse av polartorsk i Barentshavet

This report gives, and sums up, information about the geographical distribution of polar cod in the Barents Sea, useful when investigating the existence and Bocation of a possible spawning area in the western parts of the Sea. Only information available at the Institute of Marine Research in Bergen is included, and only the two sources of information most relevant to the question are included, viz. the distribution of fingerlings in August and that of the adult stock in September. These sources contains long time series of data; the 0-group distribution dates back to 1966 and that of the adult stock to 1974. Based on this information, it is difficult to reach a conclusion about a possible spawning area in the western parts of the Barents Sea. The geographical distribution of adult fish in autumn gives evidence for such a spawning area, but is also compatible with the hypothesis that the known spawning area in the south-eastern Barents Sea is the only one in this area. The distribution of polar cod 0-group in August points, however, to the fact that spawning must take place in two separate areas, since most years there are two separate concentrations of fingerlings. Since these data are sampled in August, and spawning probably takes place in early spring, the distribution of 0-group polar cod cannot done show the location of a western spawning area. Combined with a current model these data should, however, give valuable information about the location of spawning.NORSK SAMMENDRAG:I forbindelse med arbeidet med å kartlegge polartorskens gytefelter i Barentshavet, er det i denne rapporten samlet informasjon om polartorskens utbredelse i Barentshavet som kan kaste lys over denne problemstillingen. Kun informasjon tilgjengelig ved Havforskningsinstituttet er tatt med, og bare de to datakildene som synes å gi den mest relevante informasjonen om polartorskens mulige gytefelter; nemlig yngelutbredelsen i august og utbredelsen av den voksne bestanden i September. For disse to datakildene foreligger lange tidsserier, yngelutbredelsen er kartlagt tilbake til 1966, og den voksne bestanden tilbake til 1974. Det synes vanskelig, på grunnlag av denne informasjonen alene, å trekke konklusjoner angående et eventuelt gytefelt i det vestlige Barentshav. Basert på utbredelsen av voksen polartorsk om høsten synes det rimelig å anta at det må finnes et gytefelt sør eller øst av Svalbard, men fordelingen er også forenlig med en teori om at det kjente gytefeltet i den sørøstlige delen av Barentshavet er det eneste. Ut fra yngelutbredelsen i august synes det klart at det må være to separate gytefelter, da det de fleste år er to separate fordelinger av yngel. Da disse dataene er samlet inn i august, og gytingen trolig foregår tidlig om våren, kan ikke yngelutbredelsen alene angi hvor gytefeltet ligger. Kombinert med en strømmodell skulle imidlertid disse dataene kunne gi verdifull informasjon om lokaliseringen av et gytefelt i vest

Feeding Hotspots and Distribution of Fin and Humpback Whales in the Norwegian Sea From 2013 to 2018

Fin whales (Balaenoptera physalus) and humpback whales (Megaptera novaeangliae) are commonly found in the Norwegian Sea during the summer months. Records from around 1995 to 2004 show that their distribution patterns were mainly associated with those of macro-zooplankton. More recent studies conducted from 2009 to 2012 demonstrate marked shifts, with fin whale distribution related to pelagic fish distribution, decreasing densities of humpbacks, and increased densities of toothed whales. During the same period, historically large abundances of pelagic planktivorous fish in the Norwegian Sea were reported. The goals of this study were to examine the summer distribution of fin and humpback whales from 2013 to 2018 and to assess the potential association between distribution and environmental impact factors. Results suggest a pronounced northerly shift in distribution for both species, a feeding hotspot for fin whales at the shelf area between Svalbard and Norway, and one near Bear Island for humpback whales. Fin whale distribution was associated with that of blue whiting (Micromesistius poutassou) and capelin (Mallotus villosus), whereas humpback whale distribution was associated with that of euphausiids (Meganyctiphanes norvegica, Thysanoessa longicaudata, and Thysanoessa inermis), capelin, and herring (Clupea harengus). However, a significant negative spatial correlation was found between whale occurrence and the widely expanding population of northeast Atlantic mackerel (Scomber scombrus). The results of this study suggest that the prey composition of fin and humpback whales in recent years contain a large proportion of fish. The apparent northerly shift in the distribution of these whale species is largely determined by the availability of prey, but it likely is also impacted by direct or indirect interspecific interactions, especially with killer whales (Orcinus orca). Such large-scale pronounced changes in distribution seem to confirm a high degree of plasticity in fin and humpback whale feeding in the Norwegian Sea