Conservation and Natural History of the Greenland Shark
The general aim of this project is to deploy satellite tags, and collect tissues from Greenland sharks for age determination in order to better understand their movements and the age structure of the population(s).
Why this is important:
Fishing pressure and a lack of knowledge of basic natural history are threats to the future of the Greenland shark (Somniosus microcephalus), thought by some to be the longest-lived vertebrate on earth. Effective conservation and management of any fish species requires a thorough understanding of growth rates, age at first reproduction, fecundity, distribution, population structure, etc.
Depth and location alter the amount of radioactive carbon incorporated into the tissue which, in turn, impact the accuracy of the age based on radiocarbon dating. Our two proposed projects are therefore directly related in that water masses occupied and age determinations are linked.
This research will address both these issues by deploying additional popup satellite archival tags (PSATs) on sharks in Eastern and Western Greenland, and by collecting tissue samples for radiocarbon analysis. (It should be noted that the researchers have already successfully deployed PSATs on sharks in northwestern Greenland and had them remain attached for the full programmed period of 3.5 months.) PSATs deployed in both areas will be programmed to release after 1-3, and 9-12 months to provide insights into the water masses occupied. These data will, in turn, be important for our ageing studies which comprise the second portion of the study.
Eye lenses will be collected from sharks of various sizes for age determinations using radiocarbon dating. Several fishermen and fisheries biologists are willing to assist us and supplement our own efforts.
Aims and Objectives
The general aim of this project is deployment of satellite tags and collection of tissues from Greenland sharks for age determination in order to better understand their movements and the age structure of the population(s). Detailed objectives include:
- Deploy longlines in northeastern Greenland to catch (and release) Greenland sharks.
- Measure total length, girth, weight, gender, date, and location of capture sharks and release after tagging with dart tags from the Greenland Fisheries Department.
- Deploy 8 PSATs on longline-caught sharks set to release at intervals from 1-12 months.
- Collect vertebrae and eye lenses from any dead or terminally injured sharks for ageing studies.
- Determine age of shark tissue samples by bomb radiocarbon analysis (AMS 14C Dating Center, University of Aarhus, Denmark).
Greenland sharks; large, old, and incredibly slow moving. Peter Bushnell, project leader for the Save Our Seas Supported project on the Conserv ation and History of the Greenland shark, cannot really blame them. He reports from the fjords of Eastern…
In addition to the electropositive metal study we also deployed four pop-up satellite tags in western Greenland near Qeqertarsuaq (Disko Island, ~69º13 N, 53º.36 W) to study the Greenland shark’s short term movements. The tags reported in late 2011. Over…
In Greenland, the longline fishery targeting halibut (Reinhardtius hippoglossoides) is plagued by a substantial bycatch of Greenland sharks (Somniosus microcephalus). This has led to a bounty for shark hearts as proof of their elimination. We went to Greenland in May…