Life History Introduction l Strandings l Fishery Observer Program l Blubber Steroid Hormones l Frozen Tissue Archive
Life history studies describe the reproductive and survival characteristics of a species, including
- how long individuals live
- the age at which they become sexually mature and first reproduce
- how often they breed
- how long they nurse their young
- where they forage
- what they eat
Combining this data for many individuals of a species enables us to understand their growth rate potential, which is a critical factor in developing plans for effective management and conservation.
Species of Interest
Pantropical Spotted Dolphin
Eastern and Whitebelly Spinner Dolphin
Short-beaked Common Dolphin
These are the three dolphin species most impacted by the tuna purse-seine fishery in the eastern tropical Pacific, and the drift and set gillnet boats operating off the coast of California. Historically, most of the samples used in life history studies came from dolphins caught as bycatch in these fisheries. Working with this sample collection, we have developed new techniques, which can be applied to these and other cetacean species. We are now able to gather valuable life history data from small skin and blubber biopsy samples, each about the size of a pencil eraser. To learn more about this technique, click here.
Specimen Collection in the Field
Most of our specimens come from animals accidentally killed in fishing gear, or from animals found stranded on the beach. Observers working on fishing boats, or stranding team members gathering samples from a beached animal, collect the following standard data:
- Document species identification with photos, drawings, and written observations
- Record when and where it was sampled
- Measure total body length and maximum girth
- Determine gender
Whenever possible, they also include detailed morphological measurements and tissue sampling. For more, see Analysis in the lab… « less
Analysis in the Lab
Standard samples include:
- Skin and/or internal organ for molecular genetic studies
- Blubber for contaminant and isotope studies
- Teeth for aging
- Gonads for determining state of sexual maturity and reproductive status of females
- Stomachs for ID of prey species
- Head and post-cranial skeleton for morphological studies
- Internal organ samples for determining cause of death
Chivers, S.J. 2002. Cetacean Life History. Pages 221-225 in: Perrin, W. F., B. Wursig and J. G. M. Thewissen. Encyclopedia of Marine Mammals. San Diego, CA, USA: Academic Press.
Perrin, W. F. and S. B. Reilly. 1984. Reproductive parameters of dolphins and small whales of the family Delphinidae. Reports of the International Whaling Commission (Special Issue 6): 97-113.