Pathways of unauthorized fish introductions and types of management responses

Rahel, Frank J.; Smith, Mark A.

doi:10.1007/s10750-018-3596-x

Cited by 41 publications

(51 citation statements)

References 43 publications

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“…Moreover, other predatory fish such as Channel Catfish Ictalurus punctatus , Largemouth Bass Micropterus salmoides , Smallmouth Bass Micropterus dolomieu , and Walleye Sander vitreus have been introduced to the western United States and are negatively influencing native fishes and the ecosystems they support (McMahon and Bennett ; Fritts and Pearsons ; Olden and Poff ; Schade and Bonar ; Sanderson et al. ; Rahel and Smith ). Managers have implemented (or are contemplating) suppression programs for invading fishes to preserve or restore sympatric native fishes or desired sport fish populations, or both (Coggins et al.…”

Section: Discussionmentioning

confidence: 99%

“…Because of their popularity as sport fish, nonnative predatory fish have been widely introduced, both intentionally by managers (McMahon and Bennett ) and illegally by anglers (Rahel ), and have also dispersed naturally via connected waterways (Muhlfeld et al. ; Rahel and Smith ). Along with causing displacement or extirpation or both of native fishes, introduced predatory fish can add a previously nonexistent trophic level that exerts cascading, top‐down effects and alters aquatic food webs (Eby et al.…”

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confidence: 99%

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Organic Pellet Decomposition Induces Mortality of Lake Trout Embryos in Yellowstone Lake

et al. 2019

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Yellowstone Lake is the site of actions to suppress invasive Lake Trout Salvelinus namaycush and restore native Yellowstone Cutthroat Trout Oncorhynchus clarkii bouvieri and natural ecosystem function. Although gill netting is effective (Lake Trout λ ≤ 0.6 from 2012 through 2018), the effort costs more than US$2 million annually and only targets Lake Trout age 2 and older. To increase suppression efficiency, we developed an alternative method using organic (soy and wheat) pellets to increase mortality of Lake Trout embryos on spawning sites. Decomposition of pellets during two in situ experiments caused dissolved oxygen (DO) concentrations to temporarily decline to lethal levels (<3.4 mg/L) within days of application. Embryo mortalities during the first exposure period (days 1-6 following application) were high at all treatment levels (1.75-28.0 kg/m 2 ) at the substrate surface and within interstices 20 cm below the surface, varying from 97 ± 1.8% (mean ± SE) to 100 ± 0.0%, but may have been enhanced by a handling effect (exposure to sunlight). Embryo mortalities during the second exposure period (days 11-22) were highest 20 cm below the surface, varying from 78 ± 9.7% to 100 ± 0.0%. Almost all (98 ± 3.1%) Lake Trout embryos died after exposure to DO < 3.4 mg/L for >200 h during the second period. Pellets caused lethal DO for several weeks below the substrate surface, despite largely dissolving and dissipating from the surface of treated areas by day 39. Broad-scale application of pellets at 1.75 kg/m 2 following the spawning period in autumn may reduce Lake Trout recruitment and enhance population suppression because the area of 14 verified spawning sites is only 11.4 ha (0.03% of lake surface area). Pellet application may be useful in other similar systems as part of an integrated pest management approach targeting multiple life stages of invasive freshwater fish.

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Section: Discussionmentioning

confidence: 99%

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confidence: 99%

Organic Pellet Decomposition Induces Mortality of Lake Trout Embryos in Yellowstone Lake

et al. 2019

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“…This implies that factors other than prescribed agency stockings are influencing the genetic characteristics of bass populations in Tennessee. The observed incidence of hybrids in both the Tennessee and Cumberland rivers raises an important question: “What contribution do FLB × LMB hybrids make to recreational fisheries?” If the source of admixture in unstocked water bodies is angler‐mediated translocations, then education of the public and legislation that limits public access to FLB or to FLB × LMB hybrids may limit the potential unsanctioned spread of FLB in Tennessee (Rahel and Smith ). Ultimately, additional work is necessary to understand the sources of genetic admixture detected in the Tennessee and Cumberland River systems.…”

Section: Discussionmentioning

confidence: 99%

A Statewide Evaluation of Florida Bass Genetic Introgression in Tennessee

Hargrove

Rogers

Kacmár

et al. 2019

N American J Fish Manag

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The Largemouth Bass (LMB) Micropterus salmoides is one of the most popular freshwater sport fish in the United States, and managers in southeastern states have stocked its subspecies, the Florida Bass (FLB) M. salmoides floridanus, outside of the subspecies' natural range to increase the size structure of existing LMB populations. In Tennessee, fisheries for LMB are concentrated in reservoirs of the Cumberland and Tennessee River systems; however, FLB stockings have to date been restricted to two reservoirs of the Tennessee River and have varied significantly in extent and duration. We quantified levels of genetic admixture between FLB and LMB by using 38 species-diagnostic single-nucleotide polymorphisms for 979 fish sampled from 14 reservoirs within the Cumberland and Tennessee River systems. We tested for differences in genetic admixture across river systems and evaluated the relative importance of fish stockings in explaining observed levels of genetic admixture. Levels of admixture and associated variation were higher in Tennessee River reservoirs (average percentage of FLB alleles: range = 6.3-30.4%) than in Cumberland River reservoirs (range = 5.7-13.4%), but admixture was not solely related to stocking rates. The highest levels of FLB introgression were detected in Chickamauga Reservoir, the most extensively stocked reservoir in the state. Linear models identified fish stocked as a significant overall predictor of admixture, but we also observed stocked and unstocked reservoirs with similar levels of admixture, suggesting that factors other than stocking influence population genetics. Our statewide assessment of reservoir-level patterns of hybridization among black bass was performed prior to the recent expansion of FLB stocking efforts in Tennessee and thus represents a baseline for evaluation of future stocking.

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“…Unauthorized introductions of non-native fishes are a continuing problem for fisheries managers. Rahel and Smith (2018) reviewed Wyoming, USA agency records over a 57-year period to show that the greatest source of introductions was deliberate illegal release of fish by the public, and pointed to the importance of public education and enforcement to curtail these introductions. Using a literature survey, Gubiani et al (2018) showed that unauthorized introductions also dominate in Neotropical ecosystems.…”

Section: Dispersal and Factors Regulating Introductionmentioning

confidence: 99%