During a cruise to Svalbard in September 2012 a unique collection of the little known but widely distributed Atlantic spiny lumpsucker ( Eumicrotremus spinosus ) was made in the Hinlopen Strait. A total of 140 individuals (36–101mm total length) were collected using a bottom trawl. All individuals were sexed and 26 of these were also analysed for gonadosomatic index (GSI), hepatosomatic index (HSI) and stomach content. The sex ratio of the entire sample showed a strong bias towards females (75% of all examined specimens). The GSI ranged from 1.4 to 5.8% except for one female with a GSI of 20%. All females carried gonads in which eggs were clearly visible, independent of size, indicative of an early sexual maturation and an iteroparous life cycle of females. All examined specimens had almost an exclusively pelagic diet, with Themisto libellula constituting 100% of the stomach content in 80% of the examined fishes. The results are discussed in relation to diel vertical migration of Arctic zooplankton and deep migrating layers.
The aim of the study is to describe aspects of the life history of the Atlantic poacher (Leptagonus decagonus) obtained during early October 2010 and late September 2011 from the Hinlopen Strait, located between Nordaustlandet and the Spitsbergen Archipelago. Length was measured for 142 individuals, and 82 out of these were weighed, sexed and the age in years determined. The sex distribution in the population was 45% females and 55% males. Gut content examination revealed the domination of the mesopelagic and hyper−benthic calanoid Bradyidius similis that was recorded in 87% of the stomachs analysed. Overall there was a significant difference in size (length and weight) between the sexes, and a difference in length and weight at age between the sexes. There was no difference in age distribution between the sexes, but there was a larger age range within the male population than in the female population. The sexual dimorphism in size is likely linked to different reproductive strategies. This study represents the first data on the life history of the Atlantic poacher in Svalbard waters.