Aaron J. Adams

Efficacy of PIT tags and an autonomous antenna system to study the juvenile life stage of an estuarine-dependent fish

Many marine fishes use spatially distinct habitats as juveniles and adults. Determining which juvenile habitats are most important to sustaining adult populations (i.e., which habitats are nurseries) has proven difficult, in part due to challenges in estimating survival of juveniles in putative nursery habitats. Recent technological advances have made largescale tagging efforts a viable approach to estimating survival of juvenile fishes by increasing recapture rates and enabling the use of individual-identification tags. These techniques, using Passive Integrated transponder (PIT) tags and autonomous antenna detection systems (antenna), have been successfully applied in freshwater environments. This paper reports the adaptation of these techniques to estuarine mangrove creeks (salinity: 2–28‰) for research of the juvenile life stage on an estuarine-dependent marine fish,Centropomus undecimalis. Retention rate of PIT tags in juveniles >120 mm standard length was 100%, with no mortality. The antenna detection field covered 48% of the creek water column, and the antenna was experimentally determined to detect approximately 67% of tagged fish that swam through. Overall recapture rate of tagged fish by the antenna was >40%. This recapture rate is higher than the sparse data typical of traditional tag-recapture studies. A time-dependent Jolly-Seber model was fit to the data, providing estimates of capture probability (0.8) and weekly apparent survival (0.41) that will be invaluable in comparing juvenile habitats of different quality (e.g., natural versus anthropogenically degraded). This research demonstrates the viability of this approach to fish research in estuarine habitats.

Mechanisms Affecting Recruitment Patterns of Fish and Decapods in Tropical Coastal Ecosystems

The early benthic life history of fishes and decapods in tropical coastal ecosystem can be partitioned into three main stages—settlement, post-settlement transition, post-settlement stage—which culminate in recruitment. Although most species go through these early life history stages, not all species follow the same strategy. Life history strategies occur in three general categories: habitat specialists, habitat generalists, and ontogenetic shifters. Despite this variation in life history strategy, common processes affect the early life history stages of tropical marine fishes and decapods. The life history transition from planktonic larva to benthic post-larva connects oceanic and coastal habitats. However, benthic features and benthic processes affect early life history stages so that settlement and post-settlement distributions are not perfect reflections of larval supply patterns. The abundances and distributions of settlement and post-settlement life history stages result from complex interactions of larval supply, larval behavior, and the interactions of early settlers with the benthic environment. Since much of the very high mortality that occurs during settlement and early post-settlement appears to be due to predation, the direct effects of predators may be the most important factors acting on these early life history stages. Habitat selection, priority effects, predator avoidance, inter- and intra-specific competition, and aggression during and after settlement are also important influences on abundances and distributions of settlement and post-settlement fishes and decapods. The connection between nursery habitat availability and adult population abundances has been demonstrated, so it is likely that these other interactions of early life history stages with the benthic environment have demographic implications that are not yet understood.

Occurrence and persistence of non-native Cichlasoma urophthalmus (family Cichlidae) in estuarine habitats of south-west Florida (USA): environmental controls and movement patterns

The geographic scope of species introductions has increased dramatically in the last 200 years. One of the greatest challenges to understanding the ecological consequences of non-native species is that it has been difficult to identify the attributes that allow them to become established outside their native range. This challenge is compounded by anthropogenic habitat alteration that often enhances the establishment and expansion of non-native species. Fishes in the family Cichlidae are notoriously adaptive, and contribute more non-native species to North America than any other fish family. This is especially true in Florida (USA), where 18 cichlid species have become established. The Mayan cichlid (Cichlasoma urophthalmus) was first documented in south Florida in 1983, and is present in many freshwater and estuarine habitats. This study reports a northward range expansion by C. urophthalmus, demonstrates the connectivity between altered freshwater habitats and tidal estuarine habitats, and suggests that the estuarine populations are ephemeral and dependent upon colonisation from populations in altered freshwater habitats.

Quantitative assessment of a data-limited recreational bonefish fishery using a time-series of fishing guides reports

Recreational fisheries can be prone to severe declines, yet these fisheries, particularly catch-and-release, are often data-limited, constraining our ability to conduct stock assessments. A combination of catch and effort indices derived from fisheries-dependent data (FDD) gathered from fishing logbooks could be a powerful approach to inform these data gaps. This study demonstrates the utility of using different catch metrics such as indices of abundance, species richness associated with reported catch, and the success rate of targeted trips, to assess historical shifts in the trajectory of the data-limited bonefish (Albula vulpes) fishery in Florida Bay, an economically-important recreational fishery within the Caribbean Basin. We used FDD from fishing guide reports submitted to Everglades National Park to determine temporal patterns in the bonefish population over the past 35 years. These reports indicated a decline in recreational catches in Florida Bay since the late 1980s, with an accelerated decline starting in the late 1990s-early 2000s. Analyses showed an overall 42% reduction in bonefish catches. Trends in the proportion of positive trips (i.e., the probability of catching success) followed the declining catch patterns, suggesting major population changes starting in 1999–2000. As bonefish catches declined, species richness in bonefish trips increased by 34%, suggesting a decrease in bonefish abundance and/or shift in fishing effort (e.g., giving-up time, changes in preferred species). Results provide additional resolution to a pattern of decline for bonefish in South Florida and highlight the value of reconstructing time-series for the development of hypotheses about the potential driving mechanisms of species decline. Further, the data-limited nature of most recreational fisheries, and the increase in a use of catch-and-release as a fisheries management strategy point to the need to develop further data integration tools to assess population trends and the sustainability of these fishery resources.

Comparison of Retention Success for Multiple Tag Types in Common Snook

Abstract Tags are commonly used to uniquely identify fish in order to estimate population size, harvest rates, and fish behavior. However, some tags have the propensity to be shed (lost), which can bias results. To examine the shedding rates of external tags and the potential bias this introduces for common snook Centropomus undecimalis we marked adult snook with an internal 23-mm half duplex passive integrated transponder (PIT) tag (as a permanent mark) and one of two external tags: a T-bar anchor tag (44 mm; Floy, FD-68B) or a dart tag (89 mm × 2 mm; Floy, FT-1-94). Fish were tagged along sandy beaches of the Gulf of Mexico in southwestern Florida during the spawning season in 2007–2009. Short-term (37-d) external tag retention success was 100% for both tags. However, long-term (391-d) retention success was low for external tags (T-bar = 76%; dart = 38%). Given the limitations of and trade-offs among tag types, choosing the most appropriate tag will continue to challenge researchers. Until more universa...

Mapping of stakeholder activities and habitats to inform conservation planning for a national marine sanctuary

The Florida Keys is recognized as the birth place of flats fishing, but the flats fishery has historically been underappreciated by resource managers because it is a catch and release fishery. However, the fishery is increasingly threatened by habitat degradation and user conflicts. Ongoing regulatory revisions in the Florida Keys prompted us to work with flats fishing guides to document spatial fishing coverage and habitats so that this information could be included in management revisions. We used a geostatistical approach to create contour maps depicting fishing coverage and habitats, and provided this information to resource managers. This participatory GIS approach engages stakeholders in the management process, uses their knowledge of the resource, and contributes to resource and fisheries conservation. This study, in combination with research on the economic impact of the flats fishery, presents the flats fishery as an important conservation tool for the region and underscores the implication of relationships between researchers and data providers in the saltwater recreational fishery.

Bonefish in South Florida: status, threats and research needs

Bonefish (Albula vulpes) support a world-renowned fishery in South Florida, USA. However, fishing guides and anglers have been reporting significant declines in bonefish angling quality over that past three decades. In the absence of any long-term bonefish stock and ecosystem assessments, the cause of this decline in the fishery is unclear. Here we summarize our current knowledge of bonefish ecology in Florida and discuss potential causes of fishery decline. Reductions and alterations in freshwater flows from the Everglades have caused major changes in bonefish habitat, including acute (anoxic conditions) and chronic (changes in benthic flora and fauna) effects in Florida Bay and Biscayne Bay. Various pollutants from agricultural and urban runoff may also be impacting bonefish population(s) directly and/or indirectly throughout their range. Efforts to locate juvenile A. vulpes in Florida have been largely unsuccessful to date, suggesting abundances may be low, and/or juveniles have unknown habitat requirements in Florida. Further, bonefish larvae may be sourced from adult individuals outside of Florida in areas such as Cuba or Mexico, in which case bonefish conservation in other regions is highly relevant to the Florida population. Extreme weather events may have also contributed to the decline; an extreme cold spell in 2010 caused significant bonefish mortality and coincided with documented declines in the fishery. The fishery may also be impacting the population. We outline research needs and potential approaches to better understand the causes of the bonefish decline in Florida and restore populations of this ecologically and socioeconomically important species.

Bonefish (Albula vulpes) oocyte lipid class and fatty acid composition related to their development

Bonefish (Albula vulpes) are a valuable fishery resource of tropical and subtropical ecosystems worldwide. Despite their importance, there is limited information on bonefish life history and ecology. The present study aims to describe, for the first time, oocytes development and their lipid characteristics in wild bonefish during the reproductive season in different tidal flat locations in Grand Bahama Island, Bahamas. Our results have shown that Bonefish follow group-synchronous ovarian development and produce lipid-rich eggs [total lipid (TL) content was >26% of wet mass (WM)]. The major lipid class was a neutral lipid: the wax esters and steryl esters (WE-SE; >48% of TL), suggesting their use to support buoyancy and/or energy storage. Fatty acid (FA) composition of bonefish oocytes was characterized by high levels of monoenes in the neutral lipid fraction (i.e. 16:1 and 18:1n-9) indicating their probable role as energy fuel. However, the most abundant fatty acids in the polar lipids were docosahexaenoic acid (DHA; 22:6 n-3 > 15% of total polar FA), eicosapentaenoic acid (EPA; 20:5 n-3 > 13% of total polar FA) and arachidonic acid (ARA; 20:4 n-6 > 4% of total polar FA) which were selectively conserved among the tidal flat locations, suggesting their importance as essential constituents of cell membranes during the development of bonefish oocytes. Our results bring useful information concerning the reproductive physiology of bonefish and not only serve as a benchmark for determining the nutrient requirements to produce high quality eggs from bonefish captive broodstock, but also will help establish meaningful management practices for this species.