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  • Articles  (5)
  • Ecology  (5)
  • 2020-2022  (5)
  • 1
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    A comparison between circle hook and J hook performance in the dolphinfish, yellowfish tuna, and wahoo troll fishery off the coast of North Carolina (2021)
    In:  http://aquaticcommons.org/id/eprint/8676 | 403 | 2012-06-05 13:30:36 | 8676 | United States National Marine Fisheries Service
    Details
    Publication Date: 2021-06-25
    Description: We compared numbers of strikes, proportions of fish that hooked up after strikes, proportions of fish that stayed on hook (retained) after hook up, and numbers of fish caughtbetween circle and J hooks rigged with dead natural fish bait (ballyhoo)and trolled for three oceanic predator species: dolphinfish (Coryphaena hippurus), yellowfin tuna (Thunnus albacares), and wahoo (Acanthocybium solandri). Interactions were compared between circle and J hooks fished on 75 trips by two user groups (charter and recreational fishermen). Hooks were affixed to three species-specific leader types most commonly fished in this region: monofilament (dolphinfish), fluorocarbon (tuna), andwire (wahoo). Numbers of fish caught per trip and three potential mechanisms that might inf luence numbers caught (i.e., number of strikes, proportion of fish hooked, and proportion retained) were modeled with generalized linear models that considered hook type, leader type, species, user(fishing) group, and wave height as main effects. Hook type was a main effect at the catch level; generally, more fish were caught on J hooks than on circle hooks. The effect ofhook type on strike rates was equivocal. However, J hooks had a greater proportion of hook-ups than did circle hooks. Finally, the proportion of fish retained once hooked was generally equal between hook types. We found similar results when data from additional species were pooled as a “tuna” group and a “mackerel” group. We conclude that J hooks are more effective than circle hooks at the hook-uplevel and result in greater numbers of troll-caught dolphinfish, tunas
    Keywords: Biology ; Ecology ; Fisheries ; Management
    Repository Name: AquaDocs
    Type: article
    Format: application/pdf
    Format: application/pdf
    Format: 156-175
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  • 2
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    Flatfish herding behavior in response to trawl sweeps: a comparison of diel responses to conventional sweeps and elevated sweeps (2021)
    In:  http://aquaticcommons.org/id/eprint/8753 | 403 | 2012-06-11 18:33:30 | 8753 | United States National Marine Fisheries Service
    Details
    Publication Date: 2021-06-26
    Description: Commercial bottom trawls often have sweeps to herd fish intothe net. Elevation of the sweeps off the seaf loor may reduce seafloor disturbance, but also reduce herdingeffectiveness. In both field and laboratory experiments, we examined the behavior of flatfish in response to sweeps. We tested the hypotheses that 1) sweeps are more effective atherding flatfish during the day than at night, when fish are unable to see approaching gear, and that 2) elevationof sweeps off the seafloor reduces herding during the day, but not at night. In sea trials, day catches were greater than night catches for four out of six flatfish species examined. The elevation of sweeps 10 cm significantlydecreased catches during the day, but not at night. Laboratory experiments revealed northern rock sole (Lepidopsetta polyxystra) and Pacific halibut (Hippoglossus stenolepis) were more likely to be herdedby the sweep in the light, whereas in the dark they tended to pass under or over the sweep. In the light, elevationof the sweep reduced herding, and more fish passed under the sweep. In contrast, in the dark, sweep elevationhad little effect upon the number of fish that exhibited herding behavior. The results of both field and laboratoryexperiments were consistent with the premise that vision is the principle sensory input that controls fish behavior and orientation to trawl gear, and gear performance will differbetween conditions where flatfish can see, in contrast to where they cannot see, the approaching gear.
    Keywords: Biology ; Ecology ; Fisheries
    Repository Name: AquaDocs
    Type: article , TRUE
    Format: application/pdf
    Format: application/pdf
    Format: 145-154
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  • 3
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    Feeding ecology of Atlantic bluefin tuna (Thunnus thynnus) in North Carolina: diet, daily ration, and consumption of Atlantic menhaden (Brevoortia tyrannus) (2021)
    In:  http://aquaticcommons.org/id/eprint/8767 | 403 | 2012-06-10 09:01:56 | 8767 | United States National Marine Fisheries Service
    Details
    Publication Date: 2021-06-27
    Description: Diet, gastric evacuation rates, daily ration, and population-level prey demand of bluefin tuna (Thunnus thynnus) were estimated in the continental shelf waters off North Carolina. Bluefin tuna stomachs were collected from commercial fishermen during the late fall and winter monthsof 2003–04, 2004–05, and 2005–06. Diel patterns in mean gut fullness values were used to estimate gastric evacuation rates. Daily ration determined from mean gut fullness values and gastric evacuation rates was used, along with bluefin tuna population size and residency times, to estimate population-level consumption by bluefin tuna on Atlantic menhaden (Brevoortia tyrannus). Bluefin tuna diet (n= 448) was dominated by Atlantic menhaden; other teleosts,portunid crabs, and squid were of mostly minor importance. The time required to empty the stomach after peak gut fullness was estimated to be ~20 hours. Daily ration estimates were approximately 2% of body weight per day. At current western Atlantic population levels, bluefin tuna predation on Atlantic menhaden is minimal compared to predation by other known predators and the numbers taken in commercial harvest. Bluefin tuna appear to occupy coastal waters in North Carolina during winter to prey upon Atlantic menhaden. Thus, changes in the Atlantic menhadenstock status or distribution would alter the winter foraging locations of bluefin
    Keywords: Biology ; Ecology ; Fisheries
    Repository Name: AquaDocs
    Type: article , TRUE
    Format: application/pdf
    Format: application/pdf
    Format: 56-69
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  • 4
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    Seasonal and interannual variation in juvenile salmonids and associated fish assemblage in open waters of the lower Columbia River estuary (2021)
    In:  laurie.weitkamp@noaa.gov | http://aquaticcommons.org/id/eprint/14485 | 403 | 2014-02-13 04:31:50 | 14485 | United States National Marine Fisheries Service
    Details
    Publication Date: 2021-06-26
    Description: The transition between freshwater and marine environments is associated with high mortality for juvenile anadromous salmonids, yet little is known about this critical period in many large rivers. To address this deficiency, we investigated the estuarine ecology of juvenile salmonids and their associated fish assemblage in open-water habitats of the lower Columbia River estuary during spring of 2007–10. For coho (Oncorhynchus kisutch), sockeye (O. nerka), chum (O. keta), and yearling (age 1.0) Chinook (O. tshawytscha) salmon, and steelhead (O. mykiss), we observed a consistent seasonal pattern characterized by extremely low abundances in mid-April, maximum abundances in May, and near absence by late June. Subyearling (age 0.0) Chinook salmon were most abundant in late June. Although we observed interannual variation in the presence, abundance, and size of juvenile salmonids, no single year was exceptional across all species-and-age classes. We estimated that 〉90% of juvenile Chinook and coho salmon and steelhead were of hatchery origin, a rate higher than previously reported. In contrast to juvenile salmonids, the abundance and composition of the greater estuarine fish assemblage, of which juvenile salmon were minor members, were extremely variable and likely responding to dynamic physical conditions in the estuary. Comparisons with studies conducted 3 decades earlier suggest striking changes in the estuarine fish assemblage—changes that have unknown but potentially important consequences for juvenile salmon in the Columbia River estuary.
    Keywords: Biology ; Ecology ; Fisheries
    Repository Name: AquaDocs
    Type: article , TRUE
    Format: application/pdf
    Format: application/pdf
    Format: 426-450
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  • 5
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    Northern Coastal Basin surface water improvement and management plan : Northern Coastal Basin SWIM plan (2021)
    St. Johns River Water Management District | Palatka, FL
    In:  http://aquaticcommons.org/id/eprint/111 | 7 | 2011-09-29 22:35:03 | 111
    Details
    Publication Date: 2021-06-26
    Description: In recognition of the need to place additional emphasis on the restoration, protection, and management of the surface water resources of the state, the Florida Legislature, through the Surface Water Improvement and Management (SWIM) Act of 1987, directed the state’s water management districts to “design and implement plans and programs for the improvement and management of surface water” (Section 373.451, Florida Statutes [FS]). The SWIM legislation requires the water management districts to protect the ecological, aesthetic, recreational, and economic value of the state’s surface water bodies, keeping in mind that water quality degradation is frequently caused by point and nonpoint source pollution and that degraded water quality can cause both direct and indirect losses of aquatic habitats.The St. Johns River Water Management District (SJRWMD) initiated the Northern Coastal Basin (NCB) project in 1995 in response to general water quality concerns and the closure of historic shellfish harvesting areas. Potential negative impacts from current and anticipated growth on coastal resources, particularly shellfish harvesting, highlighted the need for a dedicated program to address surface water quality and estuary issues. In addition, a number of water bodies in the NCB are listed by the U.S. Environmental Protection Agency (303d list) as not having sufficient water quality to meet their designated uses. The purpose of the NCB SWIM Plan is to set forth a proactive course of action, identifying the projects that address both estuarine water quality and habitat protection, and theeffort needed to accomplish them, consistent with the levels and trends of available funding. (99pp.)
    Keywords: Ecology ; Conservation ; Fisheries ; Environment ; Planning ; estuarine water quality ; estuaries ; habitat protection ; shellfish ; pollutant load reduction goals (PLRG) ; Tolomato River ; Matanzas River ; Pellicer Creek ; Halifax River ; water quality ; coastal zone management ; wetlands ; salt marsh
    Repository Name: AquaDocs
    Type: monograph
    Format: application/pdf
    Format: application/pdf
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