10 Years Later: A Review of the Impact of the 5-fish Bag Limit for Spotted Seatrout in the Lower Laguna Madre

Jason Ferguson | Ecosystem Leader, Lower Laguna Madre Lab
10 Years Later:  A Review of the Impact of the 5-fish Bag Limit for Spotted Seatrout in the Lower Laguna Madre

Figure 1.Spring gillnet catch rates for spotted seatrout – Coastwide and Lower Laguna Madre, 1985-2017.

Figure 2.Length frequency distribution of gillnet caught spotted seatrout in the Lower Laguna Madre, 1998-2017.

Figure 3.Annual mean lengths of gillnet caught spotted seatrout in Lower Laguna Madre, 1985-2017.

Figure 4.Annual percentage of gillnet caught spotted seatrout that are 25 inches in length or greater in the Lower Laguna Madre, 1985-2017.

In 2007, Dr. Larry McKinney, who was the Director of the TPWD Coastal Fisheries Division at the time, wrote a couple of articles for this magazine discussing the need for a regional management approach for spotted seatrout (SST) in the Lower Laguna Madre (LLM).At the time, the population of trout in the LLM was in a state of decline while the rest of the Texas coast was experiencing an increase in numbers.Dr. McKinney argued that since trout do not migrate long distances over the course of their life, and because the LLM is relatively geographically isolated, a regional change in SST regulations would be more appropriate than a coastwide change.In the articles, he presented several different options for regulation changes, and using TPWD models, he predicted how each change would likely affect different life history parameters of SST in the LLM.Of the options considered, a reduction in the bag limit from 10 fish to 5 seemed to be the most appropriate, and as most are aware, that regulation was implemented for the LLM in September of 2007.

The majority of anglers I’ve spoken to in the LLM region claim that the reduction of the SST bag limit was successful and greatly benefited the fishery.In fact, positive testimony by LLM anglers helped fuel the argument for the 5-fish bag limit to be expanded further up the coast in 2014.However, not everyone agrees, and anecdotal observations are of limited value. Therefore, it is useful to take a more scientific approach and examine how the SST fishery has changed in the last 10 years. Since the maximum life span of SST is about 10 years, the impact of the regulation change should be fully realized in the entire population.To examine this impact, I used TPWD data to compare various SST life history parameters for the 10 years prior to and after the regulation change.This allowed me to not only quantifiably measure how the SST fishery has changed, but to determine the accuracy of the predicted outcomes made by TPWD in 2007.

The first parameter examined was catch rates of SST from TPWD gillnets (Fig. 1).This data provides a measure of relative abundance of the adult fish population.Higher catch rates indicate more fish in the Laguna.As you can see, following the lower catch rates experienced in the mid ‘90s through early 2000s, the LLM trout numbers started trending upwards after the regulation change. In fact, the mean catch rate from the 10 years prior to the regulation change (1998-2007) was 1.08 fish per hour, while the mean catch rate from 2008-2017 increased to 1.25 fish per hour.That may not sound like much, but it actually equates to an increase of nearly 16%, which is five times higher than the predicted 3% increase in population size.

Of course, abundance estimates aren’t the only information that can be obtained from TPWD gillnet data.Fish captured in our sampling gears are also measured, allowing us to calculate length frequency distributions, mean length, and the percentage of fish in the population larger than 25 inches.Figure 2 compares the length frequency distributions of SST from 1998-2007 and 2008-2017.Prior to the regulation change, there was a noticeable decline in larger size classes, which is an indicator of increased mortality due to fishing pressure.After the regulation change, the percentage of fish in the 20+ inch size classes increased.Naturally, the increase in the number of larger fish also led to an increase in the overall mean length (Fig. 3).The 10-year mean length increased from 18.2 (1998-2007) to 19 inches (2008-2017), representing a 4.4% increase in mean SST length after the regulation change.However, perhaps the statistic that stands out the most to all the trophy trout hunters is the percentage of trout 25 inches or greater (Fig 4).From 1998-2007, the average percentage of fish in this size class was just over 10% of the total population, while the average percentage from 2008-2017 increased to 15.6%.This represents a whopping 56% increase in the number of large trout out there, which is considerably higher than the predicted increase of 38%.

These results suggest that regional management has been very effective in the LLM and the current population is now much more robust than it was prior to the regulation change.This means that not only is the fishing better, but the trout population stands a much better chance of quickly recovering from a major freeze or other natural disasters.Perhaps even more importantly, the LLM continues to remain one of the best places in the country to go catch a trophy trout now, and hopefully for years to come.

McKinney article #1:https://www.texassaltwaterfishingmagazine.com/fishing/education/texas-parks-wildlife-field-notes/spotted-seatrout-lower-laguna-madre-a-regional-approach-restoring-world-class-fishery

McKinney article #2:https://www.texassaltwaterfishingmagazine.com/fishing/education/texas-parks-wildlife-field-notes/spotted-seatrout-lower-laguna-madre