Date of Award

5-2011

Level of Access Assigned by Author

Campus-Only Thesis

Degree Name

Master of Science (MS)

Department

Wildlife Ecology and Wildlife Conservation

Advisor

Joseph Zydlewski

Second Committee Member

Ben Letcher

Third Committee Member

Stephen Coghlan, Jr.

Abstract

Brook charr (Salvelinus fontinalis) are a popular sport fish and have experienced marked declines in size, abundance, and distribution. The sea-run form of this species has experienced a parallel decline, the causes of which are poorly understood. Growth and movement behaviors are known to interact and influence the survival and fitness of an individual. Furthermore, growth variation in juveniles is linked to life history variation in adults. We used biannual mark-recapture surveys and active telemetry to track the movement and growth of brook charr at Stanley Brook (Seal Harbor, Maine) and Cove Brook (Winterport, Maine) during 2006-2010. Individuals were captured during backpack electrofishing surveys and implanted with a 12.5 mm PIT tag for unique identification. We used a combination of continued electrofishing surveys, PITpacking, radio telemetry, and stationary PIT antenna arrays to follow these fish through space and time. Overall, we marked 7,309 individuals which resulted in 3,619 physical recapture events. Individual variation in growth rates was best explained by a model containing an interaction between season and an individual's length, mean water temperature, and instream location. Growth rates were fastest in the summer, and smaller individuals grew more rapidly than larger conspecifics. Individuals using habitats closer to the head of tide grew faster than those in upstream locations. We documented considerable stream-to-stream and year-to-year variation in the growth of coastal brook charr. The effects of repeated handling on growth appear subtle relative to other factors, but a slight negative effect was detected. Interestingly, physical habitat variation was not an important control of individual growth variation within Stanley Brook. Overall, we were able to explain 51.9% of the observed individual growth variation using our model. Our results suggest that movement is limited during the summer and winter months, but considerable movement occurs during the spring and fall. Using a weight of evidence approach, we conclude that the restricted movement paradigm applies to coastal brook charr populations on a seasonal basis. However, where movements occur, they appear to be ecologically significant, as they allow individuals to transition between important seasonal habitats.

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