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EFFECTS OF LAND USE CHANGES ON ALEWIFE POPULATION

Rita Oliveira Monteiro

Rita Oliveira Monteiro collects alewife herring on Cape Cod.

Rita Oliveira Monteiro conducts her graduate research in some of Cape Cod’s most picturesque locations: Trunk River off Falmouth’s Surf Drive, Wing Pond and Cedar Lake in North Falmouth, Waquoit’s Childs River and Quashnet River, Stoney Brook in Brewster, and Herring Brook in Eastham. But this Ph.D. candidate has been collecting alewife (one of the two river herring species) as they run into streams since March, when the water was just barely above freezing. Hardly a vacation.

Ms. Monteiro, a graduate student at the State University of New York’s College of Environmental Science and Forestry in Syracuse, will be at the Ecosystems Center for the next three years. She is working with Ivan Valiela, adjunct scientist at the center and professor in the Boston University Marine Program. Her research centers on the effects of land development on the alewife population, which has dropped precipitously in the past 50 years. Ms. Monteiro estimates a 95% decline in the species. In November of 2005, the Commonwealth of Massachusetts imposed a three-year moratorium on the harvest, possession and sale of herring.

Possible reasons for the alewife fishery decline are overfishing and by-catch (fish that are discarded because they are not the target catch). But Ms. Monterio focuses her research on the conversion of forests to developed areas and the resulting increased nutrient run-off from these watersheds into streams and estuaries where herring spawn. Alewives migrate north from mid-March to mid-May to spawn in their natal streams, and increased urban development may alter breeding and growth by reducing water quality in these streams.

The areas of study include watersheds at different levels of development, from heavily forested to urbanized. Five are on Cape Cod, two in New Hampshire and two in southern Maine. In these streams, development could affect herring breeding not only because of associated nutrient loading but because of the alteration and loss of suitable breeding habitat, such as removal of dams or marshes.

Ms. Monteiro will collect about 30 adult and 30 juvenile alewives in each study area in each season, then will measure the stable isotopes in the juveniles’ muscle tissue. The isotope data will help her identify the chemical signatures of their home stream watersheds. She will also analyze the otoliths (earbone structures behind the herring’s brain) to estimate their growth rates, and elemental composition in watersheds with contrasting levels of development.

Helping Ms. Monteiro are Falmouth Department of Natural Resources Assistant and Herring Constable, Charles Martinsen, and River Herring Wardens from Eastham, Henry Lind, and Brewster, Dana Condit.

Her efforts to provide information on the link between the alewife decline and the increased urbanization of the coastal watershed will, Ms. Monteiro hopes, give answers to what kind of land cover is specifically involved in affecting alewife populations, and provide information for marine conservation planning. “This could affect management strategies such as habitat restoration, water quality protection, establishment of reserves and the control of harvests.”

Ms. Monteiro can be reached at the MBL at 508-289-7518 and by e-mail at ritmonteiro@gmail.com