Observations of two deep-sea chimaeroids in Icelandic waters.

Long-term survey time series repeated occurrence of the deep-sea chimaeroid species small-eyed rabbitfish Hydrolagus affinis and large-eyed rabbitfish H. mirabilis have been observed at same but few locations in Icelandic waters over 23 years. For H. affinis the catch at one specific station has consisted almost exclusively of mature males over the time period. Identification of potential aggregation locations is of vital importance to natural resource management because such aggregation may render these species vulnerable to potential fishing activities.

The first global deep-sea stable isotope assessment reveals the unique trophic ecology of Vampire Squid Vampyroteuthis infernalis (Cephalopoda).

Vampyroteuthis infernalis Chun, 1903, is a widely distributed deepwater cephalopod with unique morphology and phylogenetic position. We assessed its habitat and trophic ecology on a global scale via stable isotope analyses of a unique collection of beaks from 104 specimens from the Atlantic, Pacific and Indian Oceans. Cephalopods typically are active predators occupying a high trophic level (TL) and exhibit an ontogenetic increase in δ15N and TL. Our results, presenting the first global comparison for a deep-sea invertebrate, demonstrate that V. infernalis has an ontogenetic decrease in δ15N and TL, coupled with niche broadening. Juveniles are mobile zooplanktivores, while larger Vampyroteuthis are slow-swimming opportunistic consumers and ingest particulate organic matter. Vampyroteuthis infernalis occupies the same TL (3.0-4.3) over its global range and has a unique niche in deep-sea ecosystems. These traits have enabled the success and abundance of this relict species inhabiting the largest ecological realm on the planet.

Low effective population size and evidence for inbreeding in an overexploited flatfish, plaice (Pleuronectes platessa L.).

Overexploitation and subsequent collapses of major worldwide fisheries has made it clear that marine stocks are no inexhaustible. Unfortunately, the perception remains that marine fished are resilient to large population reductions, as even a commercially 'collapsed' stock will still consist of millions of individuals. Coupled with this notion is the idea that fisheries can, therefore, have little effect on the genetic diversity of stocks. We used DNA from archived otoliths collected between 1924 and 1972 together with 2002 juvenile;s tissue to estimate effective population size (Ne) in plaice (Pleuronrctes platessa). Ne was estimated at 20,000 in the North Sea and 2000 in Iceland. These values are five orders of magnitude smaller than the estimated census size foe the two locations. Populations examined between 1924 and 1960 were in Hardy-Weinberg equilibrium, whereas populations examined after 1970 were not. Extensive testing was performed to rule out genotyping artefacts and Wahlund effects. The significant heterozygote deficiencies found from 1970 onward were attributed to inbreeding. The emergence of inbreeding between 1905 and 19070 coincides with the increase in fishing mortality after World War II. Although the biological mechanisms remain speculative, our demonstration of inbreeding signals the need for understanding the social and mating behaviour in commercially important fishes.