Recent declines in American lobster fecundity in southern New England: drivers and implications

Abstract

Lobsters in southern New England (SNE) have experienced decades of environmental stressors along with a suite of emerging diseases. We hypothesized that the sublethal effects of physiological stress resulting from increased temperatures have contributed to a decline in reproductive investment in SNE lobsters. Using the presence of epizootic shell disease (ESD) as a proxy for stress, we examined lobster potential fecundity through the number of recently extruded, early-stage eggs and their nutritional quality; realized fecundity based on counts of late-stage eggs nearing hatch; and compared realized fecundity to historical data (1980s) from the region. Generalized linear modeling revealed that female size was a significant predictor of both potential and realized fecundity as expected, but that ESD status did not result in differences in fecundity. Dry weight was the only difference in nutritional content egg–1 between non-diseased and diseased females. There was also no relationship detected between potential fecundity and any nutritional metric from non-diseased females. However, both dry weight and protein were negatively correlated with potential fecundity in diseased females. Most importantly, realized fecundity of recent-day females was significantly reduced compared to the fecundity of historical females, characterized as a 23% decrease predicted by our model. Stressful environmental conditions, particularly temperature, may have contributed to decreased fecundity over a 30-year period in SNE. Our data demonstrate that expectations around the potential for the SNE stock to rebuild need to be adjusted to this new regime of decreased reproductive output and can no longer rely on past estimates of egg production and recruitment.

The impact of ocean warming on juvenile American lobster recruitment off southeastern Massachusetts

“…Consistent with bottom temperatures observed by Pugh and Glenn (2020), mean June-July bottom temperatures modeled in our theoretical-stationary larval release area suggest that any egg-bearing lobsters continuing to make such inshore seasonal migrations would expose themselves to temperatures approaching and sometimes exceeding the 18 C upper limit of adult preference (Crossin et al, 1998). The redistribution of egg-bearing lobsters to a thermal (Shields, 2013(Shields, , 2019 and predation (Le Bris et al, 2018), as well as decreases in lobster fecundity (Goldstein et al, 2022).…”

“…The multiple factors contributing to low adult abundance in SNE are either caused by or intensified by the changing thermal habitat. These factors include increases in natural mortality due to disease (Shields, 2013, 2019) and predation (Le Bris et al, 2018), as well as decreases in lobster fecundity (Goldstein et al, 2022).…”

Carapace microbiota in American lobsters (Homarus americanus) associated with epizootic shell disease and the green gland

“…The average temperature of the LIS bottom water has risen a total of 1.6°C (0.4°C per decade) since 1976 ( Groner et al, 2018 ). The elevated temperature not only limits survival and reproduction of lobsters, but it can also make them relocate from their habitats ( National Oceanic and Atmospheric Administration, 2016 ; Quinn, 2017 ; Goldstein et al, 2022 ). In addition, increasing ocean temperature enables opportunistic marine pathogens to proliferate and increase their virulence, leading to disease emergence such as Epizootic Shell Disease (ESD; Harvell et al, 2002 ; Tlusty and Metzler, 2012 ; Shields, 2013 , 2019 ).…”

Length-weight relationship of six species of Thryssa with emphasis on the biology ofThryssa mystax from Indian waters

“…Hoda (1976) reported the fecundity Hoda (1982) and Kende (2016). A lower fecundity rate may be caused by the effect of physiological stress and egg attrition (Goldstein, 2022). In conclusion, the present study provides LWR information for six species of genus Thryssa, from which three of them showed positive allometry and the rest had negative allometric growth.…”