Studies of kelp harvesting in Nordland in 2015

Havforskningsinstituttet gjennomførte undersøkelser i forbindelse med prøvehøsting av stortare (Laminaria hyperborea) på Helglandskysten i Nordland i 2015. Totalt så ble det høstet 9.963 tonn stortare fordelt på 6 prøvehøstefelt i 2015. Tarevegetasjonen ble undersøkt vha undervannsvideo på prøvehøstefeltene og nærliggende referansestasjoner i forkant av høstingen. Det ble også gjennomført oppfølgende undersøkelser på felt som ble prøvehøstet i 2013 og 2014. I tillegg ble det samlet inn stortareplanter fra områder som ikke tidligere er tarehøstet for studier av morfologi, alder, veksthistorikk og epifytter. Effekter av prøvehøstingen på forekomst av fisk og skalldyr ble undersøkt i samarbeid med lokalkjent fisker. Undersøkelser etter prøvehøstingene i 2013 og 2014 viste god gjenvekst av tare og liten effekt av kråkebollebeiting på reetableringen. Alderen hos tareplanter innsamlet fra upåvirkede områder varierte fra 3 – 15 år, og økte med grad av bølgeeksponering. Størrelsen av tarestilker økte fram til plantene var ca 10 år gamle, og den årlige stilktilveksten økte med økende grad av bølgeeksponering. Tettheten av epifytter økte med alder fram til tareplantene var ca 8 år gamle, og epifyttutviklingen synes å gå langsommere i bølgebeskyttede områder. Det ble ikke registrert negative effekter av tarehøsting på fisk og skalldyr i Nordland i 2015.The Institute of Marine Research surveyed the kelp vegetation, before and after kelp (Laminaria hyperborea) harvesting in southern parts of Nordland county in 2013-2015. Kelp landings in Nordland in 2015 amounted to 9.963 tons split between 6 confined areas. Survey stations included both kelp harvested areas and nearby reference areas, and was performed by underwater video. In addition, kelp plants were collected from pristine areas for studies of plant morphology, age, growth and epiphytes. Recordings of fish and crab abundance one year after kelp harvesting were made using traditional catching gear. The reestablishment of kelp in areas harvested in 2013 and 2014 has been good, and grazing from sea urchins appears to have little effect on the recovery process. Age of kelp plants collected in pristine areas varied from 3 to 15 years, and increased with increased wave exposure. Kelp stipes reached their maximum size when the plants were approximately 10 years old and stipe growth increased with increasing wave exposure. Epiphyte density increased until the kelp plants were approximately 8 years old, and epiphytes appeared to develop more slowly in wave shelteterd areas. No negative impact of kelp harvesting on fish and crab abundance were detected in Nordland in 2015

Effects of kelp harvesting on fish and crabs, Flatanger 2014

The Institute of Marine Research studied effects of kelp (Laminaria hyperborea) harvesting on near shore fish and crab abundance in Flatanger, Nord-Trøndelag in August 2014. Recordings were made using fixed underwater camera systems and traditional fish and crab catching gear in kelp harvested areas and in reference kelp beds. The methods sample different species and sizes of fish, and supplement each other. There was a significant reduction of small cod and an increased amount of wrasse caught in wrasse traps on the harvested field two years after kelp harvesting, compared to pre-harvesting catches, indicating opposite effects of kelp harvesting on these groups of fish. However, the study suffers from a relatively low number of sampling units for the preharvesting recordings, and knowledge on the effects of kelp harvesting on fish and crab abundances should be supplemented by future studie

Studies of kelp harvesting in Nordland in 2014

The Institute of Marine Research surveyed the kelp vegetation, before and after kelp (Laminaria hyperborea) harvesting in southern parts of Nordland county in 2013 and 2014. Survey stations included both kelp harvested areas and nearby reference areas, and was performed by underwater video. In addition, kelp plants were collected from pristine areas for measurements of plant size, age and epiphytes. Recordings of fish and crab abundance were made using fixed underwater camera systems and traditional catching gear prior to the kelp harvesting in 2014. Kelp landings in Nordland were 5.576 tonnes in 2013 and 5.929 tonnes in 2014. Size of kelp plants increased with increasing wave exposure, and the kelp stocks in the eastern, less wave exposed parts were mainly small, and considered not suitable for harvesting at present. The reestablishment of kelp in areas harvested in 2013 has so far been good, and grazing from sea urchins appears to have little effect on the recovery proces

Distribution, Population Biology, and Trophic Ecology of the Deepwater Demersal Fish Halosauropsis macrochir (Pisces: Halosauridae) on the Mid-Atlantic Ridge

Halosauropsis macrochir ranked amongst the most abundant and widespread demersal fishes on the mid-Atlantic Ridge of the North Atlantic (Iceland-Azores) with greatest abundance at 1700–3500 m. All sizes, ranging from 10–76 cm total length, occurred in the area without any apparent spatial pattern or depth trend. Using otolith sections displaying growth increments assumed to represent annuli, the age range recorded was 2–36 years, but most individuals were <20 years. Length and weight at age data were used to fit growth models. No differences between sexes in length and weight at age were observed. The majority of samples had a surplus of males. Diet analysis showed that H. macrochir feeds on Crustacea, Teleostei, Polychaeta, and Cephalopoda, but few prey could be identified to lower taxonomical levels. The mid-Atlantic Ridge constitutes a major portion of the North Atlantic living space of the abyssal halosaur where it completes its full life cycle, primarily as an actively foraging euryophagous micronekton/epibenthos and infauna feeder, becoming a partial piscivore with increasing size

Maturity stages of shrimp (Pandalus borealis Krøyer 1838. Method for classification and description of characteristics

Pandalus borealis is a protandric hermaphrodite that shows a great variation in both age at sex change and in the proportion of males that become females. This plasticity is believed to be a phenotypic response to maximize individual reproductive success. Since 1992, we have classified all shrimp taken for length measurements into maturity stages in order to understand more of the population structure of shrimp in the Barents Sea and Svalbard area . The development of sex characters and transition from male to female shrimp was characterized by seven stages using the morphology of the endopod of the first pleopod, sternal spines and head roe. After the juvenile stage, shrimp mature first as males (Stage 2). Thereafter they become intersex or transitionals (Stage 3) before they develop into females with head roe (Stage 4). When the females mate, the roe is spawned under the abdomen and kept there by the pleopods (Stage 5), where it stays until the larvae hatch (Stage 6). Some females then enter a resting period (Stage 7), while others start on a new cycle with head roe (Stage 8).Maturity stages of shrimp (Pandalus borealis Krøyer 1838. Method for classification and description of characteristicspublishedVersio

Teinefiske etter reker i Tanafjorden

Det ble forsøkt et fiske etter reker med teiner i Tanafjorden. Teinene var designet og produsert av Anders Utsi. Forsøket startet i juli og fortsatte med to utsettinger i måneden fram til desember 2002. Resultatene viste at teinene fanget reker, men fangstene var generelt små. Når teinene ble halt, var det kun reker som var i teinen (ved noen tilfeller også små krabbe). Det var hovedsakelig reker med hoderogn i fangstene.Teinefiske etter reker i TanafjordenpublishedVersio

Stomach content compositions (% weight) at different locations (<b>Fig. 1</b>).

<p>Stomach content compositions (% weight) at different locations (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0031493#pone-0031493-g001" target="_blank"><b>Fig. 1</b></a>).</p

Study area and locations sampled with the bottom trawl.

<p>RV G.O.Sars, July 2004.</p

Proportions of males and females at individual locations shown in <b>Figure 1</b>.

<p>Proportions of males and females at individual locations shown in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0031493#pone-0031493-g001" target="_blank"><b>Figure 1</b></a>.</p