John T. Lamkin

Overlap between Atlantic bluefin tuna spawning grounds and observed Deepwater Horizon surface oil in the northern Gulf of Mexico

The 2010 Deepwater Horizon oil spill impacted the northern Gulf of Mexico (GOM) during the spring spawning season of Atlantic bluefin tuna (BFT). Overlap between BFT spawning habitat and surface oil in the northern GOM was examined using satellite-derived estimates of oil coverage, and spawning habitat models. Results suggested that although eggs and larvae were likely impacted by oil-contaminated waters in the eastern GOM, high abundances of larvae were located elsewhere, especially in the western GOM. Overall, less than 10% of BFT spawning habitat was predicted to have been covered by surface oil, and less than 12% of larval BFT were predicted to have been located within contaminated waters in the northern GOM, on a weekly basis. Our results provide preliminary but important initial estimates of the effects of the spill on larval BFT mortality, as concern continues over the appropriate management responses to impacts of the spill.

Significant reduction of the Loop Current in the 21st century and its impact on the Gulf of Mexico

[1]xa0This study examines the potential impact of future anthropogenic global warming on the Gulf of Mexico (GoM) by using a downscaled high-resolution ocean model constrained with the surface forcing fields and initial and boundary conditions obtained from the IPCC-AR4 model simulations under A1B scenario. The simulated volume transport by the Loop Current (LC) is reduced considerably by 20–25% during the 21st century, consistent with a similar rate of reduction in the Atlantic Meridional Overturning Circulation. The effect of the LC in the present climate is to warm the GoM, therefore the reduced LC and the associated weakening of the warm LC eddy have a cooling impact in the GoM, particularly in the northern basin. Due to this cooling influence, the northern GoM is characterized as the region of minimal warming. Low-resolution models, such as the IPCC-AR4 models, underestimate the reduction of the LC and its cooling effect, thus fail to simulate the reduced warming feature in the northern GoM. The potential implications of the reduced warming in the northern GoM on pelagic fish species and their spawning patterns are also discussed.

First larval record of Pterois volitans (Pisces: Scorpaenidae) collected from the ichthyoplankton in the Atlantic

The first record of a lionfish larva Pterois volitans (Linnaeus 1758) collected from the ichthyoplankton in the Atlantic was found within the Yucatan current off the Western Caribbean, near Cancun, Mexico. The postflexion larva measured 8xa0mm standard length and was collected using a neuston net aboard the NOAA Ship Gordon Gunter on April 10, 2010. Published morphological and meristic characters were initially used for identification; genetic verification using mtDNA followed. The larva showed 3 distinct pigments beneath the parietal spines that were not included in the original larval description of the species. Ageing of sagittal otoliths exhibited 15–16 daily increments indicating a possible spawn in late March. Given that adult lionfish are established along the Mesoamerican barrier reef, oceanographic patterns suggest that the likely origin of this larva may have been from the southern coast of the Mexican Caribbean to Belize or even Honduras. The Yucatan Current is a rapid means for the potential dispersal of lionfish larvae into the Gulf of Mexico and southern Florida.

Reproduction and larval biology in tunas, and the importance of restricted area spawning grounds

Tunas show a wide variety of life history strategies, spatial distributions and migratory behaviors, yet they share a common trait of spawning only in tropical and sub-tropical regions. The warm-water tuna species generally show significant overlap between spawning and feeding grounds, and longer spawning seasons of several months to near year-round. In contrast, the cool-water bluefin tunas migrate long distances between feeding and spawning grounds, and may spawn over periods as short as 2xa0months. Here, we examine the spatial distributions of tuna larvae in the world’s oceans, and examine interspecific differences in the light of adult behaviors and larval ecology. We discuss the links between larval tuna and their oceanographic environments and relate these to current knowledge of larval growth, feeding and trophodynamics, with a focus on the better-studied bluefin tunas. We show that larval tunas have moderate to fast growth rates and selective feeding habits, and thus appear to be adapted for survival in warm, oligotrophic seas. We also examine the challenges of sustainably managing species which migrate across multiple management boundaries to reach spatio-temporally restricted spawning grounds and discuss the previous and future anthropogenic impacts on tuna spawning areas.

Correction: Trophic Ecology of Atlantic Bluefin Tuna (Thunnusthynnus) Larvae from the Gulf of Mexico and NW Mediterranean Spawning Grounds: A Comparative Stable Isotope Study.

The present study uses stable isotopes of nitrogen and carbon (δ15Nandδ13C) as trophic indicators for Atlantic bluefin tuna larvae (BFT) (6–10 mm standard length) in the highly contrasting environmental conditions of the Gulf of Mexico (GOM) and the Balearic Sea (MED). These regions are differentiated by their temperature regime and relative productivity, with the GOM being significantly warmer and more productive. MED BFT larvae showed the highest δ15N signatures, implying an elevated trophic position above the underlying microzooplankton baseline. Ontogenetic dietary shifts were observed in the BFT larvae from the GOM and MED which indicates early life trophodynamics differences between these spawning habitats. Significant trophic differences between the GOM and MED larvae were observed in relation to δ15N signatures in favour of the MED larvae, which may have important implications in their growth during their early life stages.These low δ15N levels in the zooplankton from the GOM may be an indication of a shifting isotopic baseline in pelagic food webs due to diatrophic inputs by cyanobacteria. Lack of enrichment for δ15N in BFT larvae compared to zooplankton implies an alternative grazing pathway from the traditional food chain of phytoplankton—zooplankton—larval fish. Results provide insight for a comparative characterization of the trophic pathways variability of the two main spawning grounds for BFT larvae.

Projections of future habitat use by Atlantic bluefin tuna: mechanistic vs. correlative distribution models

mechanistic vs. correlative distribution models Barbara A. Muhling,* Richard Brill, John T. Lamkin, Mitchell A. Roffer, Sang-Ki Lee, Yanyun Liu and Frank Muller-Karger Princeton University Program in Atmospheric and Oceanic Science, Forrestal Campus/Sayre Hall, Princeton, NJ 08544, USA NOAA Geophysical Fluid Dynamics Laboratory, Princeton, NJ 08540, USA James J. Howard Marine Sciences Laboratory, Northeast Fisheries Science Center, NOAA National Marine Fisheries Service, Highlands, NJ, USA Southeast Fisheries Science Center, NOAA National Marine Fisheries Service, Miami, FL 33149, USA Roffer’s Ocean Fishing Forecasting Service, Inc, West Melbourne, FL 32904, USA Atlantic Oceanographic and Meteorological Laboratory, NOAA Office of Oceanic and Atmospheric Research, Miami, FL 33149, USA University of Miami Cooperative Institute for Marine and Atmospheric Studies, Miami, FL 33149, USA College of Marine Science, University of South Florida, St. Petersburg, FL 33701, USA *Corresponding author: tel: þ1-609-452-5322; e-mail: Barbara.Muhling@noaa.gov