Modeling the processes affecting larval haddock (Melanogrammus aeglefinus) survival on Georges Bank

Abstract

The ultimate goal of early life studies of fish over the past century has been to better understand recruitment variability. Recruitment is the single most important natural event controlling year-class strength and biomass in fish populations. As evident in Georges Bank haddock, Melanogrammus aeglefinus, there is a strong relationship between recruitment success and processes occurring during the planktonic larval stage. Spatially explicit coupled biological-physical individual-based models are ideal for studying the processes of feeding, growth, and predation during the larval stage. This thesis sought new insights into the mechanisms controlling the recruitment process in fish populations by using recent advances in biological-physical modeling methods together with laboratory and field data sets. Interactions between feeding, metabolism and growth, vertical behavior, advection, predation, and the oceanic environment of larval haddock were quantitatively investigated using individual-based models. A mechanistic feeding model illustrated that species-specific behavioral characteristics of copepod prey are critically important in determining food availability to the haddock larvae. Experiments conducted with a one-dimensional vertical behavior model suggested that larval haddock should focus on avoiding visual predation when they are small and vulnerable and food is readily available. Coupled hydrodynamics, concentration-based copepod species, and individual-based larval haddock models demonstrated that the increased egg hatching rates and lower predation rates on larvae in 1998 contributed to its larger year-class. Additionally, results from these coupled models imply that losses to predation may be responsible for interannual variability in recruitment and larval survival. The findings of this thesis can be used to better manage the haddock population on Georges Bank by providing insights into how changes in the physical and biological environment of haddock affect their survival and recruitment, and more generally about the processes significant for larval fish survival.

Modeled transport of winter flounder larvae spawned in coastal waters of the Gulf of Maine

“…The model was implemented using the open source ibm package FISCM (). FISCM has been used for a wide range of studies including the larval transport and retention of haddock (Petrik, ; Boucher et al ., ), bay scallops (Liu et al ., ), and the transport of Arctic and pan‐Arctic copepods (Ji et al ., ).…”

Connectivity of the bay scallop (Argopecten irradians) in Buzzards Bay, Massachusetts, U.S.A.

“…Larval tracking used an open-source IBM package, the FVCOM I-State Configuration Model (FISCM; FIS-CM, 2013). FISCM has been employed in studies on the transport and retention of haddock larvae on Georges Bank (Petrik, 2011;Boucher et al, 2013), and the physiological factors controlling the biogeographical boundaries of several Arctic and sub-Arctic copepods species (Ji et al, 2011). FISCM determined the advection of each individual through…”