Juvenile Bonefish Habitats

Background

While it may seem self-evident that healthy habitats are essential for healthy fisheries, in many cases habitat is not part of fisheries management plans. One of the challenges to including habitat in fisheries management plans is that habitat use by many species is not known. This is the case for bonefish, Albula vulpes, whose habitat use patterns are relatively unknown throughout its range. Of particular concern is identifying juvenile habitats.

Although overfishing is most often listed as causing declines of fish populations, loss and degradation of habitats is at least as important. This is especially true for fisheries that are primarily catch and release, such as bonefish, which have experienced population declines. Habitats essential to supporting juvenile fishes are called nurseries. If juvenile fish don’t have habitats where they can grow and be protected from predators, then not enough juveniles will survive to adulthood, and the fishery will decline. Nurseries are especially susceptible to habitat degradation because they tend to occur in shallow, coastal areas that are impacted by human
activities.

Potential loss of nursery habitats is especially troubling because the impacts of this habitat loss may not be felt for many years. This is especially true for long-lived species like bonefish, which can live 20 years or more. As long-lived species age, their growth rate slows and fish of a wide age range may be of similar size. Thus, it is difficult to determine the age structure of the population – are there enough young fish to replace the aging fish each year? In a worst case scenario, if very few juveniles are surviving each year, the population decline won’t be seen until the older fish begin to die off without being replaced by enough juveniles. This means that
by the time the problem is realized, it may be years too late. Since juvenile bonefish habitats remain unknown, and the potential negative impacts to the bonefish population are large, it is important to determine what type of habitats are required by juvenile bonefish. Once juvenile bonefish habitat types are identified, future research can address how widespread these juvenile habitats are, and the extent that juveniles are surviving to adulthood.

Findings to Date

More than 1,000 juvenile bonefish have been captured along sandy beaches of the Florida Keys, South Florida, Southwest Florida, and Belize. However, more than 95% of these juveniles have been genetically identified as Albula garcia, and less than 5% Albula vulpes. In contrast, genetic identification of bonefish caught in the recreational fishery if more than 97% Albula vulpes and less than 3% Albula garcia. This means that we have not yet found the primary habitats for juvenile Albula vulpes. In addition to sandy beaches, we have also sampled mangrove shorelines, seagrass beds, and rocky shorelines. The information collected in this study and discussions with fishing guides and anglers is pointing toward open sandy areas greater than four feet in depth as the likely habitat for juvenile Albula vulpes. If you find juvenile bonefish less than 6" long (not on sandy beaches), please let us know.