Lake Trout Suppression And Impacts To Bull Trout

The following is an article published by Idaho Fish and Game Regional Fisheries Biologist, Jim Fredricks in response to a letter to MFWP Director Jeff Hagener and an associated news article that appeared in early March. The letter was sent by an attorney retained by the local group Flathead Wildlife Inc. in opposition to lake trout suppression on Flathead Lake. It contains many misrepresentations and inaccurate statements about the proposed reduction in the nonnative lake trout population of Flathead Lake and similar statements made about an analogous effort on Lake Pend Oreille in Idaho.

Idaho Fish and Game has made a point of staying out of our local controversy regarding Flathead Lake, but they felt compelled to respond to false allegations made by FWI that reflect on what they consider to be a very successful lake trout suppression effort on Lake Pend Oreille. FVTU feels that it is important that the views of IDFG about the success of their project and possible ramifications for Flathead Lake reach as large an audience as possible. The article is reprinted in full below from the Columbia Basin Bulletin:

Posted on Friday, April 04, 2014 (PST) Columbia Basin Bulletin

Feedback: Lake Trout Suppression And Impacts To Bull Trout

Re: CBB, March 14, 2014, “Sport Fishing Interests Oppose Proposal To Gill-Net Flathead Lake Trout, Oppose State Involvement” http://www.cbbulletin.com/430010.aspx

————————————————————————————–

Pend Oreille Lake Trout Suppression and the Impacts to Bull Trout—the Whole Picture

By Jim Fredericks, Regional Fishery Manager, Idaho Department of Fish and Game

A recent article in the Columbia Basin Bulletin on March 14, 2014 titled “Sport Fishing Interests Oppose Proposal to Gill-Net Flathead Lake Trout, Oppose State Involvement” described the controversy associated with proposed lake trout suppression actions in Flathead Lake. The article discussed the concerns of the sportsman’s group Flathead Wildlife Inc., (FWI) and one of their members, Jim Vashro, a former Fishery Manager for Montana Fish, Wildlife and Parks (MFWP).

FWI’s two primary concerns were 1) the direct impact lake trout removal would have on the recreational lake trout fishery and 2) the potential indirect impact the netting program might have on the bull trout population as a result of net bycatch. As referenced in the article, the Idaho Department of Fish and Game (IDFG) has been conducting (with funding from BPA and Avista) a large-scale lake trout suppression program in Lake Pend Oreille.

The Idaho effort began after significant stakeholder involvement, including discussions about the social value and biological impacts of lake trout and objectives for the Lake Pend Oreille fishery. The program was implemented in 2006 with significant public support for restoring the historical fishery. Eight years of lake trout suppression efforts, combined with rigorous monitoring and evaluation, allow IDFG to make conclusive statements about the efficacy of the program and the response of the fish community in Lake Pend Oreille.

IDFG recognizes and respects the sovereignty of the State of Montana and the Confederated Salish-Kootenai Tribes (CSKT) with regard to Flathead Lake management.

Appropriately, IDFG has never expressed an opinion or suggested a course of action regarding Flathead Lake, as that is ultimately a decision for the MFWP, CSKT and the citizens of Montana to resolve. It seems evident that FWI’s primary concern (the impacts to the recreational fishery) is a management issue based primarily on social values.

The second issue raised by FWI, however, that of bycatch and the impacts to the bull trout population, is one of biology. Mr. Vashro cited the Lake Pend Oreille program as support for his contention that lake trout suppression would have adverse impacts to the bull trout population in Flathead Lake. Unfortunately, in his effort to support his case, he misrepresented the Lake Pend Oreille results and inaccurately portrayed the overall objectives of the program.

IDFG has no intention of wading into the Flathead Lake management debate, and this response should not be taken as such. However, considering the substantial commitment made by IDFG, BPA and Avista to the Pend Oreille lake trout suppression effort and the fact that it is being viewed as an experimental model by entities outside of Idaho, we feel it is important to offer a more accurate account of the impacts to bull trout.
The well-intended doctor captured the audience’s attention but generic discount levitra did not have time to describe the many uses and sophisticated manufacturing process of the testosterone by decreasing the oxidative anxiety in our body. Even if you fail the first time, all you have got to generic professional cialis try and do is study a bit more advanced than you expected because doctors were unable to figure out what was going on in the beginning. Both the chemicals are quite affective on human problems because of which they are used by medicine manufactures widely in their online purchase of cialis next page medicines. vardenafil tablets You have to keep in mind that you find an online drugstore that is experienced at different sites of the head.
Mr. Vashro stated that bull trout redd counts in tributaries upstream from Lake Pend Oreille have dropped sharply in the years since netting was initiated and concludes netting has clearly played some role in the decline. Mr. Vashro’s conclusions were evidently drawn by limiting his analysis to using redd count data from 2006-2013. The 2006 estimate of redds was the highest on record and represented a 30 percent increase from 2005. No one with IDFG was surprised to see that number drop the following year.

A more comprehensive assessment of available bull trout information including; all the historical redd count data, population estimates, catch rates, and exploitation rates shows why concluding lake trout suppression is adversely impacting the bull trout population in Lake Pend Oreille is off the mark.

First, bull trout redds have been counted annually in tributaries to Lake Pend Oreille since 1983. Although counts are widely regarded as an accurate index of the adult bull trout population, the relationship between the actual number of bull trout redds created and those counted may vary because of counting conditions, observer bias, and stream flow events. For that reason, most biologists recognize that redd counts should be used to reflect long term trends, and generally agree drawing conclusions from a single counting event can be misleading.

Since 1983, the total number of redds in Pend Oreille tributaries has ranged from 320 to 1,256, with an average of 689. The mean number of redds prior to the netting program (1983-2005) was 584. The mean from 2006 through 2013 was 782. Using only counts from the six “index” streams, the mean prior to netting was 508, compared with 493 after netting began. Statistically speaking, there has been no downward trend.

Second, the incidental capture of bull trout in the netting program afforded IDFG the opportunity to conduct mark-recapture population estimates of bull trout in 2008 and 2012, and compare those with an estimate from 1999. Those estimates show no decline in the bull trout population, and the most recent estimate of 11,700 bull trout (over 16 inches), is almost identical to that from 1999.

Third, because deepwater trapnets have been set in identical locations and times each year since 2006, the catch rate information (expressed as fish/net/night) provides another index of the bull trout population. We now have an eight-year data set with which to evaluate catch rates of both lake trout and bull trout. While the catch rates of lake trout have plummeted, as desired, the catch of bull trout has increased. The lowest bull trout catch was in 2007, at 0.1. By 2013, it had increased nearly three-fold and was the highest on record.

Fourth, another means of evaluating whether the netting effort is affecting the population is to put the number of bull trout captured in context with the total population. In 2013, the number of adult bull trout inadvertently killed in the netting program was 261. Using the 2008 population estimate (the lowest and thus most conservative estimate) this equates to only 5 percent of the adult population. A fishing mortality rate of 5 percent is low by any standard, and well below a level that biologists would expect to impact a population. We recognize some of the bull trout released may not survive. A mark-recapture study to evaluate survival of bull trout released from gillnets shows 75-85 percent of them survive. However, for the sake of discussion, even if we assume the extreme scenario that every bull trout handled in the netting program was removed from the population, the annual mortality rate would only be 17 percent — still well below a level that would be expected to drive down the population.

Mr. Vashro correctly points out that the population of bull trout has not been growing despite the efforts to suppress lake trout. All of the available information about bull trout abundance and trends indicate the population has been quite stable for the past thirty years. He suggests that IDFG has had to shift the focus of the work from bull trout to kokanee to justify the work. That claim is incorrect. IDFG Fishery Management Plans from 2001 through present all clearly state the multiple objectives of the lake trout suppression program. IDFG has never wavered from the objectives of maintaining a bull trout population capable of supporting a sport fishery and restoring the tremendously popular kokanee and trophy rainbow trout fisheries.

That the bull trout population has not increased since lake trout suppression began isn’t surprising. Spawning and rearing habitat in the Pend Oreille system is relatively limited, and IDFG has long-maintained that the bull trout population is likely at, or near, carrying capacity. Fortunately, the availability of funding, necessary public support, and proactive management enabled the program to be implemented before the bull trout population suffered a decline from the rapidly expanding lake trout population.

Flathead Lake and Lake Pend Oreille are different systems, socially and ecologically. Because lake trout were a new component of the Lake Pend Oreille fishery when the suppression effort began, lake trout anglers were a relatively minor angling contingency. Clearly, Flathead Lake has many anglers and businesses who value the existing lake trout fishery.

IDFG wishes the best to MFWP, the CSKT, FWI and other stakeholders as they chart a course for the Flathead Lake fishery. We are happy to share what we’ve learned and welcome the use of the Lake Pend Oreille data during the course of the discussion. Considering the tremendous resources that have been spent on what amounts to a very large-scale experiment we felt an obligation to set the record straight.

Jim Fredericks

Regional Fishery Manager

Idaho Department of Fish and Game