Potential connectivity among American lobster fisheries as a result of larval drift across the species’ range in eastern North America

Abstract

We used a bio-physical model to estimate for the first time the effect of larval drift on potential connectivity among American lobster (Homarus americanus) fisheries management areas over the geographic range of the species. The model predicted drift of larvae over distances of 50-805 km (mean = 129 km), which connected many management areas and caused marked spatial heterogeneity in retention and self-seeding versus export and import of larvae by different fisheries areas. Including mortality functions in the model resulted in less drift and settlement, and had complex effects on the amount, but not the incidence, of potential connectivity among fisheries. The model’s predictions received support from comparison of predicted settlement to landings six or seven years later in some (but not all) parts of the model domain. Although improvements are still needed to capture larval behaviours and spatial variability in larval release and mortality across the species’ range, this information is important to lobster fisheries management because the amount and direction of connectivity between fisheries can inform cooperative management strategies to sustain interconnected fisheries.

Dramatic decline and limited recovery of a green crab (Carcinus maenas) population in the Minas Basin, Canada after the summer of 2013

“…Lobster recruitment since 2013 in these areas has remained low compared to its pre-2013 values and appears to have been even lower than in 2013 in the year 2016 ( Wahle & Carloni, 2017 ). Potential settlement of lobster larvae in the Gulf of Maine-Bay of Fundy system and the Scotian Shelf has also been predicted by a bio-physical dispersal model of the species’ range ( Quinn, Chassé & Rochette, 2017 ) to have been extremely low in 2013 (BK Quinn, J Chassé, and R Rochette, pers. comm., 2017).…”

“…Values of the NAO index for each month were obtained from the Hurrell et al (2003) database ( National Center for Atmospheric Research Staff, 2018 ). Oceanic circulation effects were assessed by extracting potential total annual settlement (= total summer settlement) in the Minas Basin predicted by a bio-physical oceanographic model of larval dispersal, originally developed for American lobster ( Quinn, Chassé & Rochette, 2017 ) but with development times of larvae modified for eastern North American green crabs (after Dawirs, 1985 ). Both potential settlement in the previous and same year as density sampling were considered as potential predictors of crab abundance.…”

Impact of the use of different temperature‐dependent larval development functions on estimates of potential large‐scale connectivity of American lobster

“…One of the most accessible approaches to making such estimates is the use of physical oceanographic models coupled to biophysical computer models of larval dispersal (Caputi et al, 2018; Siegel et al, 2003; Silva et al, 2019). Such approaches have been used previously for the American lobster across its range (Chassé & Miller, 2010; Gendron et al, 2019; Harding et al, 2005; Incze et al, 2010; Katz et al, 1994; Quinn et al, 2017; Xue et al, 2008). These modeling studies indicated that larval dispersal potentially connects lobster subpopulations and fisheries in different locations and regions, although much uncertainty still remains concerning the quality and implications of their predictions.…”

“…These modeling studies indicated that larval dispersal potentially connects lobster subpopulations and fisheries in different locations and regions, although much uncertainty still remains concerning the quality and implications of their predictions. For example, incomplete information concerning various aspects of larval biology, including behavior, mortality, and development (Caputi et al, 2018; Gendron et al, 2019; Quinn, 2014a; Quinn et al, 2017), has been included in these models, with potentially important, but unquantified, impacts on model predictions and their realism. Ultimately, estimates of “realized connectivity” accounting for the effects of mortality and all other relevant biological and physical factors are needed to support management of lobster fisheries.…”

Long‐term trends and drivers of larval phenology and abundance of dominant brachyuran crabs in the Gulf of St. Lawrence (Canada)

“…Warmer than usual conditions in surface waters are also likely to accelerate larval development (Ouellet & Sainte‐Marie, ; Yamamoto et al, ) and possibly reduce the extent of larval drift and supply to some areas (e.g. Quinn, Chassé, & Rochette, ).…”