2004 HIGHLIGHTS WITH ADULT LARGEMOUTH BASS

• Salinity peaked at downstream sites during early fall months. Peak salinity levels at D’Olive Bay, our most downstream site, were 9.3‰ in September.
• Catch rates followed a seasonal pattern with increased catch rates typically occurring in winter, spring, and fall months and decreased catch rates occurring during summer months. Sites (D’Olive Bay, Gravine Island, Dennis Lake) with lowest catch rates were also sites (Bay Minette, Crab Creek, McReynold’s Lake) most closely connected to or part of a main river channel, while sites with highest catch rates were also sites least connected to a main river channel.
• Mean sizes also followed a seasonal pattern with increased catch rates typically occurring in winter, spring, and fall months and decreased catch rates occurring during summer months.
• The largest bass collected was 5.4 lbs. from Gravine Islsnd. Only two bass = 5 lbs. were sampled, and both were from Gravine Island.
• Few bass = age-4 were found both upstream and downstream.
• Survival was relatively low both downstream (42%) and upstream (55%).
• Significantly higher growth to age-1 was found at downstream sites relative to upstream sites.
• Bass were sampled from Monroe County Lake, and state freshwater fishing lake stocked with bass from the Mobile Delta. Similar to bass in the Mobile Delta, few bass from Monroe County Lake were = age-4 and survival was low (44%), which may indicate a genetic effect, where bass exhibit a trait in the absence of an environmental influence (i.e., coastal influences). Monroe County Lake bass were significantly greater in size at all ages than bass in the Mobile Delta, indicating an environmental effect, where bass may actually have the potential to grow to greater sizes in the absence of an environmental stress (i.e., coastal influences).
• Relative weights (“fatness” of fish) were greater at downstream than upstream sites.
• Bass consumed a greater % biomass of invertebrates downstream relative to upstream. Blue crabs and mud crabs ranked highest in invertebrate biomass consumed by bass downstream. Hence, the largest % biomass was from marine- and estuarine-derived prey types in downstream bass diets and was greater than in upstream bass diets. Diets of upstream bass consisted of a greater biomass of fish and freshwater-derived prey types.
• External tagging resulted in the tagging and release of 461 bass. Thirty-one bass were recaptured in our sampling, and anglers reported 8 recaptured bass. Bass were recaptured through our sampling and angler reports at all six sample sites. There was generally no movement between sample sites.
• The most notable movement occurred when a bass released by us in August 2003 was recaptured by an angler in January 2004 in Pascagoula, MI.
• Acoustic telemetry continued through December 2004. In order to determine return movement upstream of I-10/Causeway, five more fish from Bay Minette were tagged and released in Spring 2004 at the USS Alabama, which has been a popular tournament release location.
  • A similar number of bass were relocated at each site with 32 relocations completed at Bay Minette and 41 relocations completed at Dennis Lake.
  • Bass from both release phases were relocated in increased salinity although salinity was relatively low (<2‰).
  • Temperature patterns for Bay Minette and Dennis Lake followed a similar trend; however, temperatures for individual months were significantly higher at Bay Minette than at Dennis Lake for both release phases.
  • Mean total depth was greater at Dennis Lake than Bay Minette for the spring-released bass, while mean total depth was greater at Bay Minette than Dennis Lake for fall-released bass.
  • No significant differences in distances moved were found between sites.
  • The primary movement pattern of downstream bass was to remain in the protected side channels immediately off the main bay. However, subsets of bass moved to the main river channel (N=4) or during increasing salinity (N=2). Only one bass moved to the nearby Tensaw River channel from the Dennis Lake site. All other bass remained within Dennis Lake, with the exception of the suspected angler movement of one other bass 21.3 km upstream to Briar Lake.
  • For bass released at the USS Alabama, salinities were negligible at the Bay Minette capture site and they were 4.5‰ on the surface and 10.4‰ on the bottom. Two days post-release, 3 fish were detected in near the area of release. One fish was near the release location, one fish had moved downstream of the battleship and one fish had moved across the Tensaw River channel. On monthly trips over the following three months, no fish relocated. One year post-release, one fish, previously detected moving downstream of the battleship, was relocated upstream of the battleship but still downstream of I-10/Causeway. At no point was a fish relocated upstream of the Causeway. Also, none of these fish were found to return to their Bay Minette capture site up to 1 year after release.
• Bass were externally tagged and released at an upstream tournament, Team Jesus Bass Tournament, at Live Oak Landing along the Tensaw River. This was a collaborative effort between AU and ADWFF. Seventy-eight boats weighed-in, and a total of 362 bass were tagged and released. Only one bass was = 5 lbs. Sampling occurred 4, 13, and 23 days post-release and numbers of bass recaptured decreased through time. Mean distances moved away from the release generally increased through time. A concentration of bass at the release site was still evident at 13 days post-release but was not present by 23 days post-release. Eight bass were reported by anglers. Of these eight bass, one was reported dead by an angler, the lunker bass was recaptured, one bass was recaptured in the mouth of Dennis Lake, and two bass were released at other tournaments—the farthest distance from the tournament release was 32.5 km upstream. Both anglers indicated that they were fishing previous and known tournament release sites.

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