Modeling the effects of fishing and implications of the design of marine protected areas: juvenile fish responses to variations in seafloor habitat

The effects of fishing and implications of the design of marine protected areas have been modeled with attention to juvenile fish responses to variations in seafloor habitat. The model was applied to a theoretical patch of hard-bottom substratum and to a case study based on seafloor distributions at Stellwagen Bank National Marine Sanctuary (Gulf of Maine, Northwest Atlantic). Shape of response surfaces patterns that show relationships between juvenile cod (Gadus marhua) survivorship and density as well as movement rate were similar no matter what the functional response type. It was seen that juvenile cod movement rates and post-settlement density were critical for predicting effects of marine protected-area size on survivorship. Habitat change caused by fishing was seen to have significant negative effects on juvenile cod surviving. It showed use of marine protected areas can be ameliorating.