Sea Pact funding support to the University of North Texas's (UNT's) Marine Conservation and Aquatic Physiology Laboratory (MCAPL) research to compare the effectiveness of probiotics (live microorganisms that benefit their host) to antibiotics, in order to increase growth rates and reduce mortality in commercially important marine fish. Trials are presently being conducted for yellowtail amberjack and red drum, but the findings, and the methods developed will certainly be applicable to other species of marine finfish important to aquaculture. Current mortality rates in some marine fish species can be as high as 90% at the early stages, and use of antibiotics to reduce mortality can lead to the spread of antibiotic-resistant bacteria and public health concerns.

The goals of the proposed work are to compare the effectiveness of probiotics (live microorganisms beneficial to host health) to broad-spectrum antibiotics on growth and survival of two commercially important fish species; yellowtail amberjack (Seriola lalandi) & red drum (Sciaenops ocellatus). While growth rate can be high often reaching 50% per day, mortality can exceed 90% in most marine larval fishes. Broad-spectrum antibiotics, such as quinolones, have been used to reduce the incidence of disease from overcrowding in aquaculture, and as an anti-bacterial agent in larviculture. We will determine if probiotics (Lactobascillus rhamnosus) improves growth, survival and feed conversion efficiency during fish development, linking fish health to the intestinal microbiome. Our work addresses the global problem of the use of antibiotics in aquaculture, specifically in the developing world, from which the US imports >60% of its seafood. Use of antibiotics in aquaculture results in the emergence of antibiotic-resistant bacteria, which threatens human and animal health, as well as increasing public concern that farmed seafood is not sustainable and safe to consume. The work employs a probiotic (good bacteria) approach to marine fish aquaculture, which may in the long term offer an alternatives to antibiotics and help ensure a sustainable and safe seafood supply in the U.S. and ultimately the world. By providing data to show effectiveness of probiotics for fish health, we will support aquaculture of two important ocean species, and indirectly encourage the increase of aquaculture personnel using probiotics to enhance production, thereby reducing disease and reliance on antibiotics.

The major objectives of the present proposal are to determine the effects of a commercially available strain of probiotics on red drum and amberjack larval growth and survival and, 2) compare the effects of probiotics with those of larvae grown with antibiotics.
The proposed project is part of a larger project whose ultimate objective is to develop a novel set of probiotics for marine fish culture in order to provide a sustainable alternative approach to antibiotics, in order to protect human and animal health while providing a safe and economical fish supply.

The UNT project is continuing to advance research utilizing probiotics as an alternative to antibiotics for improving growth and survival in marine finfish aquaculture, and reduced use of antibiotics in the marine environment.