Payne, M.P. et al. 1990. Recent fluctuations in the abundance of baleen whales in the southern gulf of Maine in relation to changes in selected prey. Fishery Bulletin, U.S. 88:687-696.
Presented by Becky Sheiko and Alison Dean
BACKROUND INFORMATION:
The fish in this study was the Sand Lance Ammodytes spp.
- They are small eel-like fish
- They inhabit primarily sand shores
- Schools consisting of several thousand
- Found from N. Labrador to Cape Hatteras
A little backround information on the whales in the study:
Fin whale Balenoptera physulus
·
Identified by white chevron on back
- Found inshore and offshore
- Ranges: Artic Circle to Greater Antilles
- Mainly feed on small fishes, crustaceans and squids
Humpback whale Megaptera novaeangeliae
- Major defining feature are the long pectoral flippers
- Usually inhabit island banks or continental shelfs
- Ranges: N. Iceland to West Indies
- Seasonal migration
- Mainly feed on krill and small schooling fish
Right whale Eubalena glacialis
- Major identifying feature are callosities on head
- Habitat is near shore in shallow water
- Ranges: Iceland to E. Florida
- Feed on small crustaceans
Sei whale Balenoptera borealis
- Near shore and offshore animal
- Ranges: Artic Circle to NE Venezuela
- Feed on surface plankton, krill, small schooling fish, squid
- Feeds primarily where food is abundant
HYPOTHESIS:
The spatial distribution and abundance of baleen whales in the Gulf of Maine can be characterized as a series of ecological responses to human-induced changes in the abundance of planktiverous finfish.
STUDY AREA:
- The study area was called Stellwagen Bay. It is located off the tip of Cape Cod and adjacent to Massachusetts.
- This is an area of high biological productivity
- Whale watching is a major industry here and provided a lot of the data on whale abundance
METHODS:
- Data collection on the occurrence and distribution of the whales was collected by naturalists working aboard commercial whale watching vessels during the study period of 1982-88.
- Data on Sandlance populations was collected by the National Marine Fisheries Center during spring bottom-trawl surveys
- Data on Copepod populations were also collected by National Marine Fisheries using the Hardy Continuous Plankton Recorder
RESULTS:
- Two graphs were illustrated in the article showing the amount of copepods and sandlance on one graph and showing each whale species estimated populations on the other graph.
- The results showed that when there was an abundance of sandlance the estimated number of humpback and fin whales were greater.
- When the copepod populations were greater there were less humpback and fin whales and many more right and sei whales.
- The graphs were directly proportional in relation to amount of sandlance and copepods and the distribution of the different types of whales seen.
DISCUSSION:
- The data suggests that the major changes seen in the abundance and distribution of whale species from 1982-88 were not independent of eachother.
- The ability of the fin whale to exploit other resources other than the sandlance enabled it to remain in the area in times of low sandlance abundance where as the humpback was generally not seen in the area during low sandlance abundance.
- Competition between sandlance and other planktiverous whales provide for interesting dynamics. Sandlance also feed on copepods so when the populations are low due to environmental conditions or whale predation, the sandlances are basically forced to compete with the right whales for resources.
- Sei and right whales were most abundant during periods of documented low adult sandlance densities and observed copepod maximum densities.
CONCLUSION:
- This paper has examined species interactions between sandlance, (as prey and competitor) and the abundance of four species of baleen whales in the Southern Gulf of Maine. The interpretation of these results provide useful management insights into the relationships between planktiverous finfish and the cetacean community.
HUMAN IMPACT:
- The replenishing of the right whale populations is contingent upon the abundance of other finfish stocks, which are currently depleted due to human-impact.
BIBLIOGRAPHY:
Field Guide to North American Fishes, Whales, and Dolphins. Boscbung et al. 1997. Mammals. Knopf. New York:Random House. Pp772-79.
Berta, A., J. Sumich. Marine Mammals: Evolutionary Biology. New York: Academic Press.
Internet source: http:// www.coastalstudies.org/stellwagen/teleost.htm
[Course Homepage] [Syllabus] [Lecture Schedule] [Lab Schedule] [Student Presentations] [Marine Mammal Links]
