Heather Judkins

Cephalopod biodiversity in the vicinity of Bear Seamount, western North Atlantic based on exploratory trawling from 2000 to 2014

Bear Seamount (BSM) is the most inshore seamount in the New England Seamount chain. It is located within the U.S. Exclusive Economic Zone and is contained within the recently established Northeast Canyons and Seamounts Marine National Monument. In 2000, the National Oceanic and Atmospheric Administration’s (NOAA) National Systematics Laboratory began an exploratory trawling program to document nekton diversity at BSM and its vicinity. Here, we summarize eight exploratory sampling cruises conducted between 2000 and 2014, and describe the cephalopod biodiversity and assemblage structure around BSM. Over the course of 174 deep–midwater and 56 bottom tows, 5088 cephalopods were identified, measured, and documented. In total, 77 species were collected at BSM; 75 species were collected from midwater tows and 28 from benthic tows. Rarefaction curves did not reach an asymptote, suggesting that additional sampling will collect more species. Seventeen species accounted for 75% of the total midwater and bottom catch, including: Illex illecebrosus (n = 605), Magnoteuthis magna (n = 568), Abraliopsis morisii (n = 518), Abralia redfieldi (n = 358), Mastigoteuthis agassizii (n = 336), Histioteuthis reversa (n = 273), Taonius pavo (n = 239), Haliphron atlanticus (n = 195), Brachioteuthis beanii (n = 160), Ornithoteuthis antillarum (n = 153), Pterygioteuthis gemmata (n = 141), Pyroteuthis margaritifera (n = 120), Vampyroteuthis infernalis (n = 101), Chiroteuthis veranyi (n = 33), Bolitaena pygmaea (n = 30), Graneledone verrucosa (n = 11), and Stauroteuthis syrtensis (n = 29). Non-metric multidimensional scaling (NMDS) of significant analysis of similarity (ANOSIM) results showed that the 2000 cruise was different from other years, meteorological winter was different from other seasons, and that day and night shallow samples were different from each other and all other depths. Based on seasonal size variation in the most abundant taxa, we propose hypotheses of year-round, winter, and spring spawning for future critical assessment. This extensive description of the offshore cephalopod assemblage may be used to assess vulnerability to future environmental changes and human activities.

Cephalopods in the potential prey field of sperm whales (Physeter macrocephalus) in the northern Gulf of Mexico.

Cephalopods of the northern Gulf of Mexico are widely distributed and provide an important food source for a variety of marine animals. Sperm whales are year-round residents in the northern Gulf of Mexico. Prey availability has been proposed as an explanation for this non-migratory whale population. To examine this explanation, a short pilot cruise was conducted during the summer of 2009 to test equipment and to obtain preliminary observations. Then the 3-month Sperm Whale Acoustic Prey Study (SWAPS) was conducted during the winter/spring of 2010 to sample the mid-water pelagic community for possible prey of sperm whales. It also compared sperm whale distribution and prey composition across habitats of the northern Gulf of Mexico. This paper focuses on the cephalopod diversity within the mid-water pelagic community and assesses potential prey of the endangered sperm whales.

Recent Advances in Cephalopod Science. CIAC 2015 Special Issue.

The papers in this small collection represent examples of the output from the 2015 meeting sponsored by the Cephalopod International Advisory Council in Hakodate, Japan. Papers focusing on cephalopod diversity can be found in a special issue of Marine Biodiversity (volume 47, Issue 3), while papers focusing on ecology will be published in a special issue of Hydrobiology. The papers herein, as may be expected, focus on the natural history of a range of cephalopod species. Cephalopods inhabit an enormous range of habitats and consequently their natural history is widely variable. They tend to be fast growing, short-lived species, although this general paradigm has been challenged by varying age estimates of the giant squid, Architeuthis dux (see Grist and Jackson 2007), and the longevity of brooding in the deep sea in the octopus genus Graneledone (Robison et al. 2014). The longstanding view of a single spawning event followed by mortality is now known to have many variations (Rocha et al. 2001). However, much remains unknown because of the oceanic nature of some of these animals, the difficulty in their capture, and their general elusiveness. Even our knowledge of some aspects of the biology of heavily fished species is limited. Hence the observations of multiple pelagic egg masses of the Humboldt squid reported herein by Birk et al. represent a genuine advance in our knowledge. Prior to this paper, only a single Humboldt squid egg mass had been reported, despite almost 1 million tonnes of this species being landed annually (Arkhipkin et al. 2015). Another squid species subjected to substantial fishing pressure in parts of its range is Illex argentinus. Catches of this species reached 400,000 tonnes per annum prior to stock collapse, yet natal origins of some of the spawning groups are not known, and the paper by Schroeder et al. contributes to this research area using landmark analysis of body forms to show the variation in growth of different spawning groups. Growth of cephalopods does seem to be greatly affected by environmental conditions. For example, under El Niño conditions it was found that Dosidicus gigas matured at smaller sizes and younger age (Hoving et al. 2013). Takahara et al. examine the temperature effects on another ommastrephid, Todarodes pacificus, for possible early maturation rates. JOURNAL OF NATURAL HISTORY, 2017 VOL. 51, NOS. 43–44, 2565–2567 https://doi.org/10.1080/00222933.2017.1389385