TEXAS FISHERIES ASSESSMENT HISTORY

Documented declines in population survey results contradict some agency claims.

By: Walter West

The Texas Parks and Wildlife Department (TPWD) conducts surveys of fish populations within Texas Lakes. These electrofishing surveys are performed over a controlled period of time each year and the fish caught per hour are computed. Comparison of these data, lake-to-lake and year-to-year, provides biologists a means of assessing fishery productivity within the state. As of 8/8/02, electrofishing data posted at www.tpwd.state.tx.us covers the years from the mid-eighties to 1998. The web site states that these data are posted in response to “Senate Bill 1”. The fish population survey data are summarized herein. Some data were also acquired directly from TPWD field offices to provide an assessment for years subsequent to 1998 that TPWD had not posted as of 8/08/02. Review of all these data indicates a decline in large mouth bass populations is prevalent throughout lakes whose fisheries are being managed by TPWD.

The chart below was derived from 14 years of TPWD electrofishing results from Lake Conroe and illustrates an indisputable and dramatic decrease in the fishery productivity since 1987.

Data from other Texas lakes also indicate a significant decline in bass populations has occurred since the mid-nineties. Tables 1 & 2 that are included herein provide the history of Large Mouth Bass fishery assessment in twelve popular Texas lakes in the period from 1986 to 2000. These tables were derived from data posted on the TPWD web site as of 8/08/02. Note that in these tables the maximum catch rate on each lake is listed directly below the most current data that TPWD has posted, and in every case the current catch rates are much smaller than the maximum catch rates. As examples, Lake Fork catch rates decreased from 533.5 per hour in 1993 to 103.5 in 1999, and Lake Conroe catch rates decreased from 246.7 per hour in1989 to 35 in 1998. Sam Rayburn catch rates decreased from 337 per hour in 1994 to 74 in 2000.

TABLE 1 – TPWD LM BASS ELECTROFISHING

CATCHES per HOUR @

YEAR	LAKE FORK	LAKE CONROE	SAM RAYBURN	toledo bend	CHOKE CANYON	RIChland CHAMBERS
1986	70.5	159	12.5	54.7	60	N.A*
1987	103	579	31.8	44.8	N.A.	2
1988	76.5	207.6	106.8	61	N.A	13.5
1989	310	246.7	218.4	268.7	89	25.6
1990	454	98.5	301.6	120.8	94.5	N.A.
1991	296	151.5	197	178.4	137.4	N.A.
1992	264	83.4	333.5	348.3	193.5	70.7
1993	533.5	90	209.5	188	284.5	N.A.
1994	371	96.5	337	358.3	167.4	54.6
1995	347	65.5	154	184.7	184.5	N.A.
1996	336.5	26	138	151	25	117
1997	413	31.5	156	145	66.7	N.A.
1998	459	35	269.5	128.5	57.5	54.5
1999	103.5	N.A.	153**	N.A	N.A	N.A.
2000	N.A.	N.A.	74**	N.A.	N.A.	N.A.
Maximum Posted	533.5 in 93	579 in 87	337 in 94	358.3 in 94	284.5 in 93	117 in 96

Note: Source is TPWD electrofishing data base posted @ tpwd.state.tx.us as of 8/08/02

* N.A. – Not available - not posted @ tpwd.state.tx.us

** Data source TPWD regional field office

Other lake populations are also exhibiting the same trend as shown in Table 2.

TABLE 2 – TPWD LM BASS ELECTROFISHING

CATCHES per HOUR @

YEAR	SOMER-VILLE	AMISTAD	FALCON	PALE-STINE	LAVON	MONTI-CELLO
1986	N.A.	18.4	N.A	26.4	N.A	56.7
1987	197.3	N.A	24	122	61	182
1988	N.A.	34.8	N.A	124	N.A	145
1989	84	N.A	N.A	155	N.A	304
1990	N.A.	N.A	30	313.5	44	379.3
1991	76	76	N.A	245.5	N.A	180
1992	200	N.A	87	163	N.A	154.2

1993	N.A	82	N.A	219	121	337
1994	N.A	N.A	N.A	312.6	N.A	214
1995	N.A	N.A.	63	186.5	N.A	274
1996	36.5	59.5	N.A	46	9	428.7
1997	N.A	N.A	N.A	157.5	N.A	130.5
1998	N.A	N.A	42	59	N.A	112.7
Max. Posted	200 in 92	82 in 93	87 in 92	313.5 in 90	121 in 93	428.7 in 1996

There are many possible reasons for the observed decrease. Prior to1996, electrofishing fishing site selection was made by field biologists. It is possible that a bias has been introduced into the electrofishing results by the 1996 change in TPWD survey protocol to random selection of electrofishing sites on each lake, although TPWD biologists in Austin have said the change in protocol is not significant to the results. Also, some independent biologists have expressed concern over the practice of stocking Florida strain bass in lieu of native strains. In short, they are concerned that this practice is circumventing the evolutionary process and can have negative consequences. Certainly fish kills have a negative affect upon productivity and it should be noted that on average there are over 200 fish kills per year that are reported by TPWD. That’s 18 reported fish kills per month, or 4.5 per week. TPWD attributes a miniscule number of these reported fish kills to disease. For every fish that is killed in one of these episodes there is undoubtedly a much greater number that are rendered unhealthy by the conditions causing the kill, and poor reproduction and growth rates is a consequence. The conditions that cause these fish kills can and should be controlled and corrected.

The tables document a decrease in bass populations evident from accepted TPWD assessments. In conclusion, data from TPWD population surveys indicate a significant decline in the states recreational bass fisheries is occurring even though TPWD press releases quite often convey a very questionable message claiming just the opposite. In a 6/4/02 press release downplaying concern over one of the two-hundred per year Texas fish kills that occurred on Lake Bastrop, TPWD stated; “Rayburn is having a phenomenal year” and in a 12/6/99/ press release stated; “Anglers may not be catching many bass these days but it’s not for a lack of fish”. . . These are remarkable statements when you consider that TPWD creel surveys and tournament statistics also indicate a decline in Texas fishery productivity. They only detract from TPWD creditability.