2003 HIGHLIGHTS WITH AGE-0 OR YOUNG-OF-YEAR LARGEMOUTH BASS

• Recruitment to age-1 was assessed in March of 2003 and indicated no differences in CPE across all sites, however, age-1 bass were larger at D’Olive Bay (mean = 176 mm) than at McReynold’s Lake (mean = 153 mm), and were also larger at Gravine Island (mean = 175 mm) than at McReynold’s Lake and Dennis Lake (mean = 155 mm).
• In 2003 3,465 YOY largemouth bass were collected from April-December.
• Swim-up dates did not vary among sites in 2003, however, our results indicate a more protracted spawning period in 2003 (early March to late May) than 2002 (early March to late April-early May).
• Growth patterns deviated from our 2002 results, showing fast growth occurring at D’Olive Bay and relatively slow growth occurring at the remaining 5 sites. This is in comparison to the fast growth that occurred at D’Olive Bay, Bay Minette, Crab Creek, and Gravine Island, and slow growth at McReynold’s Lake and Dennis Lake in 2002.
• Relative abundance patterns also varied from our 2002 results. In general, YOY bass were more abundant downstream than upstream in 2003, with a reverse pattern exhibited in 2002.
• Diets were composed of, and dominated by the same taxa found in 2002.
• Like our 2002 results, there were no differences in the timing of, or size at piscivory among sites, however the percent occurrence of fish in the diets (by size and time) was greatest at D’Olive Bay and Bay Minette, with the remaining 4 sites exhibiting low percent occurrence. In 2002, D’Olive Bay showed the highest percent occurrence of fish, but only Dennis Lake showed a low percent occurrence. All other sites exhibited moderate occurrence of fish in their diets in 2002.
• The abundance of fish in the diets of YOY at D’Olive Bay, appears to be strongly related to the abundance and availability of estuarine fish prey (primarily rainwater killifish) as indicated by our collections. The high availability of these fish is also a likely mechanism for the consistently fast growth at D’Olive Bay.

2003 HIGHLIGHTS WITH ADULT LARGEMOUTH BASS

• Salinity peaked at downstream sites during late fall months. Peak salinity levels at D’Olive Bay, our most downstream site, were 4.8‰ in November. The lower magnitude and delay in peak salinity was likely due to heavy rains during spring through summer months.
• Catch rates were generally lower for throughout the year, and a seasonal pattern in catch rates was not as obvious possibly due to high water levels. Sites (D’Olive Bay and Gravine Island) with lowest catch rates were also sites most closely connected to or part of a main river channel, while sites (Bay Minette, Crab Creek, McReynold’s Lake) with highest catch rates were also sites least connected to a main river channel. Dennis Lake catch rates were more representative of sites less 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 5.2 lbs. from McReynold’s Lake. Only two bass = 5 lbs. were sampled, and both were from upstream sites.
• Few bass = age-4 were found both upstream and downstream.
• Survival was relatively low both downstream (47%) and upstream (52%).
• Significantly higher growth to age-1 was found at downstream sites relative to upstream sites.
• 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 374 bass. Fourteen bass were recaptured in our sampling, and anglers reported 7 recaptured bass. Bass were recaptured through our sampling and angler reports at all six sample sites. There was generally no movement between sample sites with the exception of 2 bass that moved or were moved from their Crab Creek release site to their recapture site in Bay Minette.
• Acoustic telemetry work began in Spring 2003 with the release of 20 bass at one downstream site, Bay Minette (N=10), and one upstream site, Dennis Lake (N=10), to determine the potential for salinity to affect movement. Another set of 20 bass were released in a second phase (Fall 2003).
  • A similar number of bass were relocated at each site with 39 relocations completed at Bay Minette and 43 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.
  • One bass from each site was collected in electrofishing samples and released in good condition. Capture of one transmitter tagged bass from Bay Minette was also reported by an angler.

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