Scott Hardin

Variability of Electrofishing Crew Efficiency, and Sampling Requirements for Estimating Reliable Catch Rates

Abstract Comparisons of electrofishing catch rates were conducted on two lakes in central Florida; sampling precision was examined in five other lakes. Significant differences were found among crews for various sizes (adults, subadults, quality) of largemouth bass Micropterus salmoides, bluegill Lepoinis inacrochirus, and redear sunfish L. microlophus. Results were not consistent between lakes, and rankings of crew catches varied among size categories. The number of samples required to estimate largemouth bass catch per minute with confidence limits that are within 10% of the mean at the 80% confidence level ranged from 4 to 110 (median, 19), based on catch rates from seven central Florida lakes. From 2 to 28 samples (median, 5) would be required to estimate largemouth bass catch per unit effort within 20% of the mean. For bluegill, the number of samples required to yield confidence limits within 20% of the mean ranged from 4 to 83 (median, 17). Precision ofwithin 20% ofthe mean is recommended for fisheri...

Revisions of the Fish Invasiveness Screening Kit (FISK) for its application in warmer climatic zones, with particular reference to peninsular Florida.

The initial version (v1) of the Fish Invasiveness Scoring Kit (FISK) was adapted from the Weed Risk Assessment of Pheloung, Williams, and Halloy to assess the potential invasiveness of nonnative freshwater fishes in the United Kingdom. Published applications of FISK v1 have been primarily in temperate-zone countries (Belgium, Belarus, and Japan), so the specificity of this screening tool to that climatic zone was not noted until attempts were made to apply it in peninsular Florida. To remedy this shortcoming, the questions and guidance notes of FISK v1 were reviewed and revised to improve clarity and extend its applicability to broader climatic regions, resulting in changes to 36 of the 49 questions. In addition, upgrades were made to the software architecture of FISK to improve overall computational speed as well as graphical user interface flexibility and friendliness. We demonstrate the process of screening a fish species using FISK v2 in a realistic management scenario by assessing the Barcoo grunter Scortum barcoo (Terapontidae), a species whose management concerns are related to its potential use for aquaponics in Florida. The FISK v2 screening of Barcoo grunter placed the species into the lower range of medium risk (score = 5), suggesting it is a permissible species for use in Florida under current nonnative species regulations. Screening of the Barcoo grunter illustrates the usefulness of FISK v2 as a proactive tool serving to inform risk management decisions, but the low level of confidence associated with the assessment highlighted a dearth of critical information on this species.

Rapid assessment for a new invasive species threat: the case of the Gambian giant pouched rat in Florida

The Gambian giant pouched rat (Cricetomys gambianus) is a large rodent that has established a breeding population in the Florida Keys. Should it successfully disperse to mainland Florida, it could continue spreading through much of North America where significant negative ecological and agricultural consequences could result. We rapidly developed the information for implementing an efficient and successful eradication program before dispersal to the mainland occurs. This included development of monitoring and indexing methods and their application to define the animals range, the development of baits attractive to Gambian giant pouched rats, efficacy testing of toxicants, and development of bait-delivery devices that exclude native animals. Gambian giant pouched rats appeared confined to the western two-thirds of Grassy Key, but have dispersed across a soil-filled causeway west to Crawl Key. We identified preferred habitat characteristics and potential dispersal pathways. We developed photographic and tracking tile methods for detecting and indexing Gambian giant pouched rats, both of which work well in the face of high densities of non-target species. We identified a commercial anticoagulant bait and we developed a zinc phosphide (an acute toxicant) bait matrix that were well accepted and effective for controlling Gambian giant pouched rats. We also developed a bait station for delivering toxic bait to Gambian giant pouched rats without risk to native species. We consider that the criteria are met for a successful eradication to commence.

A Florida Marine Ornamental Pathway Risk Analysis

An expert panel of 18 importer, wholesaler, retailer, producer, harvester, researcher, extension, and agency representatives implemented a known risk analysis process to assess risks associated with the marine ornamental pathway. The participants produced a literature review, marine ornamental trade description, assessed the ecological risks to Florida waters, determined the escape risk at each link and node in the pathway, and suggested risk mitigation actions. Annually, the global marine ornamental trade includes 1,500 fish species, 200 coral species, and 500 invertebrate species (excluding coral), with sale of approximately 20 million fish specimens, 10 million invertebrate specimens (excluding coral), and 10 million coral pieces. Currently, 28 exotic ornamental marine fish species have been observed in Florida waters. Two of the 28 fish species (a species complex) are established as reproducing populations in mid-Atlantic and South Atlantic waters. Participants examined the potential for economic, environmental, or perceived (social or political) effects as a consequence of marine ornamental species becoming established in Florida waters. They were very certain the potential economic costs were low and the economic benefits high based upon literature and general knowledge. Potential and real environmental effects were judged to be low based upon literature and their combined observations. However, the participants were very certain the perceived consequences, social and political, were high based upon concerns identified in the scientific literature and the use of emotive language in public media when nonindigenous species are discussed. Risk mitigation activities were suggested for the unlicensed direct consumer sales link and the consumer node.

Assessment of the Risks of Transgenic Fluorescent Ornamental Fishes to the United States Using the Fish Invasiveness Screening Kit (FISK)

AbstractThree species of transgenic fluorescent ornamental fish are commercially available to the public in the United States—Zebra Danio Danio rerio, Black Tetra Gymnocorymbus ternetzi, and Tiger Barb Systomus tetrazona. Despite qualitative assessments of the risks of these transgenic fishes by the U.S. Food and Drug Administration and two state agencies, critics argue that the risk assessment and approval processes were not transparent and that the results were never published or otherwise open to scientific scrutiny. We used an internationally recognized risk screening tool, the Fish Invasiveness Screening Kit (FISK), to provide a transparent, peer-reviewed assessment for the conterminous United States. We found that the three transgenic fluorescent ornamental fishes in question represent a low risk of invasiveness. Any risk is limited to the warmer regions of the country. No potential for hybridization with native species, little history of invasiveness elsewhere, a lack of traits associated with pers...

Risk Analysis of Barramundi Perch Lates calcarifer Aquaculture in Florida

Abstract Two Florida state agencies (Florida Fish and Wildlife Conservation Commission [FWC] and Florida Department of Agriculture and Consumer Services) have regulatory and management programs to reduce the potential for escape or release of nonnative fishes from aquaculture facilities. The barramundi perch Lates calcarifer, a large, predatory euryhaline fish native to the Indo-Pacific, is classified as a conditional species by the FWC. Aquaculturists may possess this species only under strict biosecurity requirements. In 2006, a barramundi perch aquaculturist in central Florida initiated fee fishing by the public in outdoor culture ponds. The FWC conducted a risk analysis to assess the probability and potential consequences of barramundi perch population establishment in Florida, specifically considering the increased risk of illegal barramundi perch introduction into state waters to create a sport fishery. Using a generic risk analysis review process, a stakeholder panel determined that the overall ris...

Risk Screen of Freshwater Tropical Ornamental Fishes for the Conterminous United States

AbstractThe trade in ornamental fish is increasingly viewed as a major source for the introduction of invasive species into the environment. However, few ornamental fishes are established and widespread in the conterminous United States, and fewer still are thought to cause noticeable environmental impacts. To better evaluate the risk of this pathway, we conducted a risk screen of 34 important freshwater ornamental fish species by using the Fish Invasiveness Screening Kit (FISK) version 2 for the conterminous United States. Screens from three to five independent assessors resulted in categorization of 91–100% of the species as noninvasive. The low climate match of these mostly tropical species largely confines establishment risk to subtropical regions, primarily peninsular Florida, and to isolated thermal refuges (e.g., geothermal springs) in otherwise unsuitable climates. Few data on impacts exist for tropical ornamental fish in the conterminous United States, and there is little evidence for the occurre...