Source–sink recruitment of red snapper: Connectivity between the Gulf of Mexico and Atlantic Ocean

Abstract

Geopolitical fishery management boundaries are often misaligned with the ecological population structure of marine species, which presents challenges for assessment and management of these species. Red snapper, Lutjanus campechanus, is an iconic and heavily exploited species in both the US Gulf of Mexico and off the southeastern US Atlantic coast and is managed separately in the two jurisdictions. It is hypothesized that the Atlantic red snapper stock is sustained partially by larval subsidies from the Gulf of Mexico. Here we use a biophysical modeling approach to

Retention and export of planktonic fish eggs in the northeastern Gulf of Mexico

“…That study is an additional demonstration of how considering ocean circulation in combination with biological data is fundamental to understanding how different processes work together, and would present another hypothesis regarding connectivity between the WFS and the Carolinas. Karnauskas et al (2022) have previously supported this position by providing compelling evidence that Red Snapper on the southern WFS heavily subsidize their stocks in the southeastern US Atlantic Coast via export of larvae that are spawned south of Tampa Bay. Notably, Figures 1 and 5 suggest these subsidies may also originate from areas north of Tampa Bay, which would increase the size and potential importance of these progeny sources.…”

“…This suggests that the long‐distance offshore movement of fish eggs potentially resulting in export could possibly reach the Florida Keys and be entrained in the Florida Current and continue its course in the Gulf Stream up to the southeastern United States, where similar fish assemblages occur. Indeed, recreational and commercial harvest occurs off North and South Carolina for some of the same species (e.g., snapper‐grouper complex) that are captured on the WFS (Karnauskas et al, 2022; Overton et al, 2008). Connectivity between the WFS snapper‐grouper complex and the one from the Carolinas could exist because of the possible export of the fish eggs and larvae away from the WFS (Denit & Sponaugle, 2004; Hare & Walsh, 2007; Karnauskas et al, 2022).…”

“…Indeed, recreational and commercial harvest occurs off North and South Carolina for some of the same species (e.g., snapper‐grouper complex) that are captured on the WFS (Karnauskas et al, 2022; Overton et al, 2008). Connectivity between the WFS snapper‐grouper complex and the one from the Carolinas could exist because of the possible export of the fish eggs and larvae away from the WFS (Denit & Sponaugle, 2004; Hare & Walsh, 2007; Karnauskas et al, 2022).…”

“…To investigate the movements of eggs and larvae, a variety of techniques are now being employed such as larval tagging (i.e., incorporation of isotopes or chemicals by the embryo from the mothers or via incubation), DNA sequencing (i.e., genetic analysis leading to identification of species), or biophysical circulation models (i.e., numerical simulation of behavior‐influenced trajectories) (Jones et al, 2009; Karnauskas et al, 2022; Thorrold et al, 2002). Weisberg et al (2014) used a numerical circulation model, the West Florida Coastal Ocean Model (WFCOM), which is similar to the one employed for the Deepwater Horizon (DWH) oil spill (e.g., Weisberg et al, 2017), to explain the movement of Gag ( Mycteroperca microlepis ) larvae on the West Florida Shelf (WFS).…”

“…Egg distributions observed by the FLRACEP egg monitoring program can potentially be modified by subsequent, variable egg export or retention on the WFS after spawning (Karnauskas et al, 2022), which could interfere with the use of data from the egg survey as a local fisheries management index. If egg production is a rough proxy for spawning stock biomass, variable loss of eggs through export would interfere with interpretation of the egg abundance time series, especially because loss of eggs (via export) is likely to be highly variable from year to year (Walsh et al, 2009).…”