Evaluating environmental influence on growth, maturity, and subsequent recruitment dynamics in Georges Bank haddock (Melanogrammus aegelfinus)

Recent analyses indicate that there may be an environmental determinant of haddock recruitment dynamics; specifically, the magnitude of the autumn bloom on Georges Bank (GB) is highly correlated with recruitment of the GB haddock stock the following year. Individual fish allocate surplus energy derived from food into growth and reproduction. Immature fish are able to direct all surplus energy into growth, whereas mature fish distribute surplus energy into both growth and reproduction. Consequently for haddock, during ‘bloom booms,’ one might expect to observe above average reproduction in mature fish and above average growth in immature fish, while in ‘bloom busts,’ the opposite might be observed (i.e. below average reproduction and below average growth of immature fish).  We measured annual otolith increments for 1,879 GB haddock, age 1-12, collecting in 1997-2008. Using increment distance as a proxy for annual growth, we explored the links among the environment (fall bloom) and growth across age, sex, maturity and spawning history (first-time vs. repeat spawners).  This 12-year period provided contrast in both recruitment (survivor ratio) and fall productivity (chlorophyll a magnitude). Otolith-derived growth histories indicate that components of the population responded differently to environmental productivity, providing insights into energy allocation and recruitment dynamics.