Catch and Exploitation of Shoal Bass in the Flint River, Georgia, USA: Implications for Harvest Restrictions

2019

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Standard weight (Ws) equations have been proposed for a variety of fishes, including many of the black basses Micropterus spp. We developed Ws equations for Shoal Bass M. cataractae by using the traditional regression‐line‐percentile (RLP) technique and the relatively new empirical‐percentile (EmP) method. Length and weight data for 9,058 Shoal Bass from 15 populations were used in this analysis. These fish were collected from 1978 to 2017 by various agency and university personnel from most of the known populations across the species’ range in Alabama, Florida, and Georgia. The resulting Ws equations were log10W = 3.243·log10L − 5.490 for the RLP technique and log10W = 1.225·log10L + 0.415·(log10L)2 – 3.052 for the quadratic EmP technique, where W is weight (g) and L is TL (mm). Unlike the quadratic EmP equation, the RLP equation exhibited a slight length‐related bias on each end of the length spectrum, so we recommend the EmP technique as the preferred equation for this species. To assess fish population size structure, we also propose minimum lengths for five standard TL categories of 18, 28, 35, 43, and 51 cm for stock, quality, preferred, memorable, and trophy sizes, respectively. Development of a Ws equation and standard TL categories will aid biologists in evaluating and monitoring Shoal Bass populations as part of continuing conservation efforts.

Section: Resultsmentioning

confidence: 99%

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confidence: 99%

Proposed Standard Weight (W_s) Equation and Standard Length Categories for Shoal Bass

Bonvechio

2019

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“…Where Shoal Bass populations are robust enough to support sport fisheries, management tools such as daily creel and size limits have generally been effective at conserving stocks (Ingram and Kilpatrick ; Woodside et al. ; Sammons ). In other areas, stocking has been used to restore or supplement Shoal Bass populations.…”

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confidence: 99%

“…Conversely, Shoal Bass in the Flint and Chipola River basins have shorter life spans (up to 11 years), grow rapidly, and exhibit higher total annual mortality (49–57%; Ingram and Kilpatrick ; Woodside et al. ; Sammons ). Whether these observed differences in movement patterns and demographics represent clinal variation, local adaptation, or are the result of habitat alteration is currently unclear because these basins differ in their latitude, elevation, natural habitats, and degree of anthropogenic alteration.…”

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confidence: 99%

Genetic Population Structure of Shoal Bass within their Native Range

Taylor

Tringali

et al. 2018

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Endemic to the Apalachicola River basin of the southeastern USA, the Shoal Bass Micropterus cataractae is a fluvial‐specialist sport fish that is imperiled because of anthropogenic habitat alteration. To counter population declines, restorative stocking efforts are becoming an increasingly relevant management strategy. However, population genetic structure within the species is currently unknown, but it could influence management decisions, such as brood source location. Leveraging a collaborative effort to collect and genotype specimens with 16 microsatellite loci, our objective was to characterize hierarchical population structure and genetic differentiation of the Shoal Bass across its native range, including an examination of structuring mechanisms, such as relatedness and inbreeding levels. Specimens identified as Shoal Bass were collected from 13 distinct sites (N ranged from 17 to 209 per location) and were then taxonomically screened to remove nonnative congeners and hybrids (pure Shoal Bass N ranged from 13 to 183 per location). Our results revealed appreciable population structure, with five distinct Shoal Bass populations identifiable at the uppermost hierarchical level that generally corresponded with natural geographic features and anthropogenic barriers. Substructure was recovered within several of these populations, wherein differences appeared related to spatial isolation and local population dynamics. An analysis of molecular variance revealed that 3.6% of the variation in our data set was accounted for among three larger river drainages, but substructure within each river drainage also explained an additional 8.9% of genetic variation, demonstrating that management at a scale lower than the river drainage level would likely best conserve genetic diversity. Results provide a population genetic framework that can inform future management decisions, such as brood source location, so that genetic diversity within and among populations is conserved and overall adaptability of the species is maintained.

“…). The Flint River in Georgia supports a popular fishery for Shoal Bass, and recent research demonstrated that harvest was high enough to justify a 381‐mm minimum length limit (Sammons ), which was enacted in September 2014. The 3‐year exploitation study used for the length‐limit evaluation afforded a unique opportunity to examine the effectiveness of instituting a catch‐and‐release season in terms of location and size of area, both of which have been shown to be important factors in the success of APAs (Jennings ; Halpern ; Vandeperre et al.…”

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confidence: 99%

The Effects of Regulated Area Location and Size on the Effectiveness of a Catch‐and‐Release Season for a Riverine Black Bass

2019

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Catch‐and‐release areas are an extension of the concept of aquatic protected areas, which implement protective measures at a broad spatial scale in an attempt to increase conservation efforts. Also, catch‐and‐release areas are commonly used to regulate sport fisheries, particularly in specific areas during the spawning season. However, the size and location of catch‐and‐release areas are rarely evaluated in terms of their effects on the success of these regulations in protecting these species. Empirical exploitation data were used with an age‐structured model to explore changes in population biomass and size structure of Shoal Bass Micropterus cataractae in the Flint River, Georgia, with simulated changes in the location and size of catch‐and‐release areas during the spawning season. Annual exploitation of Shoal Bass with no catch‐and‐release area was 0.257 and was reduced 0–21% when a catch‐and‐release regulation was simulated in a specific reach. Models predicted significant increases in population biomass and size structure using catch‐and‐release reaches as short as 33 km, but this was contingent upon which specific reaches were designated as catch and release. As area size increased, population biomass and size structure of the population increased, but the rate of increase depended upon the specific areas incorporated. Designation of the entire reach would decrease annual exploitation by 50%, but large portions of the study area could be designated as catch and release with little changes in population biomass or size structure due to low harvest rates. This study illuminated the importance of spatial patterns of harvest in determining effectiveness of catch‐and‐release areas, which should be an important consideration in the placement of such aquatic protected areas.