Tagging and Otolith Microchemistry Evidence for Non-Linear Growth in New England Monkfish (Lophius americanus)

Monkfish is one of the most highly valued finfish fishery species in the northeastern United States, yet very little is known about its basic biology including growth which is currently assumed to be linear based on age results from vertebrae. Here, we present tagging and otolith data that call into question linear growth and rather support a more biologically reasonable asymptotic growth pattern. From a multi-year tagging program (6,176 releases and 282 recaptures) we were able to glean growth information from 46 individuals. Daily growth increment was found to be negatively correlated to length (r² = 0.19, p < 0.01) and using this information we were able to model non-linear growth curves and associated Von Bertalanffy growth function parameters.  Tagging results agreed very well with another line of inquiry involving otolith microchemical signatures. Specifically, strontium/calcium ratios (Sr/Ca), which were verified to mirror the seasonal temperature cycle for monkfish (and hence annuli), also indicated a pattern of decreasing growth with age and size. While some subjectivity existed for interpreting Sr/Ca data, the real strength of this technique was in establishing the width of the first annulus which was quite large and consistent with rapid early growth in monkfish.