I just received this data from Matt Mauck. It includes the combined data of both the TX and OK Gill Net Survey. There are 4 charts in addition to his write-up.
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Fisheries management staff with the Oklahoma Department of Wildlife Conservation (ODWC) and Texas Parks and Wildlife Department (TPWD) recently completed annual winter gillnetting at Lake Texoma. This tool allows the collection of trend data commonly used to evaluate specific sportfish species, notably striped bass, within the lake.
As many of you have suspected, relative density of striped bass is currently lower than the traditional range of fluctuation (Figure 1 - solid line). However, when looking at larger sized striped bass, the reduced catch is not as drastic (Figure 1 - dashed line). We believe this decline in relative density is an artifact of not only dam passage during 2015 floodwater releases but also a reflection of reduced recruitment during recent drought years. Striped bass spawning success is largely dependent on spring inflow events allowing striped bass to travel long distances up the Red and Washita Rivers. Sufficient flow and distance is required for the semi-buoyant eggs to stay in suspension until hatching (several days). With some exception, much of the 1980's, 1990's, and 2000's were characterized as above average precipitation across Oklahoma and produced fairly consistent recruitment we have grown accustomed to. Recent years of drought, with exception, have yielded sub-optimal spawning opportunities and produced several weak year classes
A subset of our gillnet catch was aged using a bony structure in the head of fish known as an otolith. Our aging data suggests that 2011 and 2014 were particularly poor years for recruitment and resulted in weak year classes (Figure 2 - note lack of Ages 2 and 5). Both of these years were characterized by exceptionally low river inflows during the spawning season. Two year old fish are generally the most numerous mode of fish collected during our sampling. However, as illustrated in Figure 3, a large gap exists where this age of fish should show up (12-16 inches). On the other hand, 2008 and 2010 were particularly strong year classes. These fish are still apparent in the population but are reducing in number due to older-age. Intermediate year class strength characterized other years.
Let me offer some HOPE……………..
There are still respectable numbers of striped bass in the lake and most are of larger sizes. Figure 1 (dashed line) illustrates that the relative density of larger fish is within the range of traditional fluctuation. Furthermore, the current population reflects an all-time high on the percentage of fish greater than 20” within the lake. While this is a little misleading due to the missing 2014 year-class, it suggests that most fish you are going to encounter will be of quality size. Fish that were collected were very robust in condition. A common metric used in fisheries management to describe fish condition is known as relative weight (Wr). An “ideal” fish has a score of 100 and generally fluctuate between 90-100 for striped bass and white bass during the winter at Texoma. Recently collected striped bass (>20”) and white bass (>12”) averaged Wr scores of 117 and 111, respectively! They contained high amounts of body fat and developing gonads which are good signs for the coming spawning season.
Although too small to be effectively collected with our gillnets, we anticipate an abundant 2015 year class was produced. The larger sizes of this cohort were represented in our catch and are reflected by the 8-10 inch fish in Figure 3. These fish will become more noticeable in the coming months and will help rebuild the population……..help is on the way.
The relative density of white bass is currently higher than what we have seen in nearly 20 years (Figure 4.) These fish will help fill in the temporary void of smaller striped bass and contribute to harvest opportunities. As many of you likely remember, white bass provided a significant component of harvest several years ago when striped bass were difficult to come by.
The current shad population within the lake is very high and coincides with angler reports. ODWC targeted shad netting this past fall confirmed substantial increases in relative densities of both threadfin and gizzard shad. The mild winter we experienced has translated into high shad survival and an abundance of food.
Hopefully, this brief report has provided you with a better understanding of the current situation at Lake Texoma and has left you with hope for the near future.
Southcentral Region Supervisor - Fisheries Division
Oklahoma Department of Wildlife Conservation
2021 Caddo HWY
Caddo, OK 74729P = (580) 924-4087