TROUT WATCHERS PROGRAM

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The Trout Watchers Program is a project where volunteer recreational anglers across Louisiana collect age and growth information on large spotted seatrout (25 inches or greater total length). These data are used to supplement information on these large fish contained in the Louisiana Department of Wildlife and Fisheries' (LDWF) Age & Growth database.

Project objectives were to initiate a volunteer-based data-collection effort, and to assess its potential in increasing our understanding of these large fish and the anglers that pursue them. It must be noted that the fish sampled for the Trout Watchers Project (a voluntary, angler based, data collection effort) were not collected randomly, therefore the data do not truly represent the population. As such, they cannot be used directly in stock assessments. However, they can be used to help evaluate some trends seen in those assessments.

Of the 260 otoliths received thus far, 6 were not usable as they either had no sampling date, or had otoliths from 2 separate fish in the same sample envelope. That left a total of 254 usable otoliths over the 2-year project period. Considering the unique nature of the program, and the type of the data required for analysis, this percentage of usable samples is very acceptable.

The Trout Watchers data can be used as an index to validate stock assessment model outputs. For example, the most recent spotted seatrout stock assessment conducted by the LDWF revealed that recruitment (a measure of the number of fish that enter a class during some time period) of female spotted seatrout was high for the years 1998 and 1999. Anglers reported increased numbers of large trout in recent years, and creel surveys conducted by LDWF personnel for the Marine Recreational Fisheries Statistical Survey (MRFSS) also showed an upward shift in length frequencies of harvested trout during 2001-2002. A larger percentages of older female trout were also sampled from random collections made through the LDWF's age and growth project, all of which indicate contributions from these strong year-classes.

Some trends were consistent in the data between the two years of the Trout Watchers program. Most of the sampled fish were between 4-7 years old. In 2004, 4-year old fish were a smaller fraction of the total numbers of Trout Watchers samples, while 5-year old fish were a larger fraction. This is consistent with a very strong 1999 cohort growing into the sizes sampled by the program. The 1999 cohort was present as 4-year olds in 2003, but much of the cohort was still too small to be sampled. More of the cohort was within the size range in 2004, increasing its representation in the samples.

Several projects are examining whether or not trout are larger in the West and East portions of the state relative to the Central, and why, as outlined below.
LSU's Coastal Fisheries Institute has agreed to conduct micro-chemistry analysis, including stable isotopes, of the Trout Watcher otoliths. It is hoped that this analysis will reveal chemical markers that can be used to identify the nursery areas as well as any major movement patterns of these fish throughout their lives. Along with the older spotted seatrout from Trout Watchers, young-of-the-year from fishery-independent LDWF Marine Finfish Program surveys will also be analyzed. This research should provide information on how the species migrates and feeds within different estuarine systems in the state.

UNO's Nekton Research Laboratory will be conducting a project designed to determine the relative nutrient contribution of each habitat to the growth and survival of spotted seatrout in coastal Louisiana waters. For example, anecdotal evidence suggests that trout found in Barataria Bay exhibit different growth patterns than in other bay systems. By assessing the recent feeding histories using stable isotopes and fatty acids, we can determine whether trout in Barataria Bay are feeding at a different or less productive trophic level of the food chain or if the food web structure and available nutrients in Barataria Bay differs from adjacent trout habitats.

NOTES - these were in the first year's report, and remain pertinent:

1. Based on literature, males identified at a particular length group would generally be older than the average female in the same length group, as females grow faster than males. Four fish that were recorded as male by the anglers may have been outliers or may be mis-identified as to sex. Without any mechanism to validate sex data, it is unclear if these fish were classified as the wrong sex. If the project is continued, gonad sampling may have to be initiated or a more detailed sexing key will have to be created.
   
2. Very few fish of these large fish were collected from the central area of the state. Again, if the project is continued more effort will have to be focused on this area, perhaps through manning fishing rodeos, etc.

Thanks to this volunteer driven project, we have increased our knowledge on the age composition of large trout. Prior to this project we had collected a total of 128 pairs of otoliths for large trout. We look forward to another year of angler cooperation and especially thank the Louisiana Sea Grant College Program for their assistance, advice, and support and the Louisiana State University's Coastal Fisheries Institute for the aging validation and continued analysis.

For more information, please contact:

Randy Pausina
Biologist Program Manager
Marine Fisheries Division, LDWF
(225) 765-2415