A comparison of cod life-history parameters inside and outside of four year-round groundfish closed areas in New England, USA

From 1994 to 2002, five major year-round closed areas were established in the Gulf of Maine and on Georges Bank to promote recovery of groundfish species, including Atlantic cod (Gadus morhua). Here, we present life-history data for cod sampled within and next to four of the five closed areas to test the hypothesis that closed areas benefit cod. We found a positive effect of closure status on cod age, length and growth for three of the four closed areas; contrary results for the fourth area (Jeffreys Ledge) may be due to recreational fishing pressure. Diet results were not consistent across closed areas, but for the two areas farthest from shore (Cashes Ledge and Closed Area II), cod tended to have higher gut fullness and higher trophic niche breadth (based on stable isotopes) inside vs. outside. Body shape analysis revealed a consistent effect of closure status on cod morphometry with cod inside closed areas exhibiting less streamlined bodies. We discuss this apparent selection for more sedentary cod with lower productivity potential but highlight the demographic result (i.e. higher age and greater size inside closed areas) as critical considerations for resource managers that are designing or altering the configuration and/or scale of closed areas to protect and rebuild demersal fish species.