Title: Squaretails, Biology and Management of Maine’s Brook Trout

Author: Forrest Bonney

Copyright Date: 2007

Price: $10 at http://www10.informe.org/webshop_ifw/index.php?p=1859&c=12&storeID=2

ISBN-13: 978-0-9794363-0-7

Maine anglers and those who travel to the Pine Tree State in pursuit of trout have long been aware of the value of the brook trout fishery it provides.  Not until recently, however, has the unique worth of Maine’s wild and native brook trout populations been widely exposed.

Forrest Bonney’s new book, Squaretails, Biology and Management of Maine’s Brook Trout, comes at the heels of the Eastern Brook Trout Joint Venture, a collaborative project evaluating brook trout populations throughout their native range in the United States.  Preliminary results from the Joint Venture are showing that Maine represents the last stronghold for native brook trout, containing more brookies in their historic range than any other state.  A heightened focus on brook trout in Maine sets a perfect stage for Squaretails, where Bonney attempts to provide a compilation of brook trout history, biology, and current status in the state from the perspective of both angler and fisheries manager.  

The history of fisheries management is rooted in the attempt to reverse declines in popular fisheries and maintain fishing quality over time.  While most people can easily relate to this concept, further understanding of the practice of fish management is often lacking.  Bonney attempts to bridge this gap in understanding between biologists and the public by describing in detail the research and data collection practices undergone in the fisheries field and why biologists do certain things.

In the book, Bonney, who has been a fisheries biologist for the Maine Department of Inland Fisheries and Wildlife for 34 years, illustrates perhaps the best case yet for responsible stewardship of Maine’s brook trout resources.  He describes the long history and current status of brook trout fishing in Maine, including historical accounts of trophy squaretails caught in the state, and changes in the fishery over time resulting from the decline of brook trout populations in many waters. 

Forrest Bonney not only thoroughly describes the biology of brook trout in Squaretails; he also documents a fairly complete history of research and management practices that relate to brook trout in the state of Maine.  He explains the current threats to brook trout populations, as well as the future research needs to allow for proper stewardship of this valuable resource well into the future. 

Mark McCollough provides captivating cover art and other illustrations, and Ethan Nadeau and others provide excellent photography and illustrations, adding a valuable artistic element to the book.    

Squaretails is the most complete resource on Maine brook trout currently available and is a must read for Maine anglers and brook trout enthusiasts everywhere.  This book, as well as a more technical version of the same content are published by the Maine Department of Inland Fisheries and Wildlife, and can be purchased at http://www10.informe.org/webshop_ifw/index.php?p=1859&c=12&storeID=2 . 

Ongoing research at Washington State University continues to focus on answering questions important to the fish culture and minimizing impacts on native fish populations.  Professor Gary Thorgaard’s Center for Reproductive Biology raises thousands of cloned juvenile rainbow trout.  Scientists at the center study disease resistance, stress response and growth rates, all of which may have important implications for the future of fisheries, particularly in the northwestern United States.

Read more about the research laboratory here

Scientists have discovered a fish that can live for months at a time out of the water!  Recent observations have identified that the mangrove killifish, which lives in swamps in areas like Florida and Belize, spends a good portion of its life living inside trees at the water’s edge.  When pools of water dry up, the fish apparently slithers into cracks and spaces in the logs of mangrove trees.  What a cool way to combat dry climate!

Read more about the mangrove killifish here 

Recent research from Oregon State University has raised a considerable amount of concern about the role of hatchery fish and their use in salmon recovery efforts.

The study has shown that domesticating salmon in the hatchery environment can significantly reduce their reproductive potential, so that individuals do not contribute to future generations nearly as much as wild fish do. 

While the study calls to question the role of hatchery fish in recovery, I think that hatchery salmon still play a significant role in providing a sport fishery, and buffering the impacts of angling on wild salmon.

Concerns about the genetic (and other) consequences of mixing hatchery and wild salmon may become even more considerable as a result of this work.  But I think the real question is whether or not we can even recover wild salmon without the help of hatcheries, especially considering the incredibly high percentage of hatchery fish making up many of our salmon runs on both coasts.

Full story from Science Daily

This week I was able to get some pictures of kokanee salmon during their annual spawning run up the tributary to a local lake. 

Kokanee (Oncorhynchus nerka) are the landlocked form of sockeye salmon, kind of similar to landlocked atlantic salmon found in many northeastern U.S. lakes.  Native forms of kokanee are found in many lakes that currently have, or have had runs of sockeye salmon from the Pacific Ocean.  It is believed that these native stocks arose from sockeye salmon offspring that stayed in inland lakes after hatching, instead of returning to the ocean. 

But the kokanee that most people are probably familiar with are those that have been stocked in inland lakes by fish and game departments to provide additional fishing opportunities.  This is the case with the fish I was observing this past week. 

One of the coolest things about these fish is that they take on an amazing red color in preparation for spawning, as opposed to the silvery color they possess prior to spawning.  Their color is such that one can walk along the shoreline of a kokanee spawning river and easily see each spawning fish. 

Unlike Atlantic salmon, species of Pacific salmon are semelparous, which means that they spawn once and die.  We observed thousands of kokanee spawning in the stream, as well as a number of dead carcasses of fish that had expended all of their energy spawning, and died.  There were tons of raccoon tracks and bird tracks on the shoreline, and at one point, there was a place along the shore where a mink had apparently pulled a number of kokanee from the river and eaten their heads, which contain the highest energy content in the fish’s body.

Kokanee are a popular sportfish and play a significant role in cycling nutrients in the ecosystems they inhabit.  They consume zooplankton and fish in the lake environment, spawn in the streams and die, where animals and insects consume them, excrete nutrients, many of which return to the aquatic ecosystem, feeding phytoplankton, which feed zooplankton…..and the cycle continues.  And aside from that, they’re fun to fish for and pretty cool to check out during the spawning run!

Just when you thought you’d heard it all…..

Japanese scientists have found a way to successfully cause one species of fish to produce the offspring of a totally separate species, through the injection of the other species’ hormones at the early developmental level.  In other words, scientists can cause salmon to produce trout!!!  Genetic testing has apparently proven this method to be extremely effective, and experts hope to use it to help recover populations of rare and endangered fish species through what they call “surrogate broodstocking”. 

The technique was first tested in Japan, and Idaho researchers plan to look into using it to help recover populations of sockeye salmon.

See the full story here

Check out this recent article by the Association of Fish and Wildlife Agencies about Colorado cutthroat trout restoration activities.

Some results from a study investigating the performance of rainbow trout in southern Maine are posted below, courtesy of the Maine Department of Inland Fisheries and Wildlife, and Sebago Region Assistant Regional Fisheries Biologist Jim Pellerin.  These results were also posted in another network blog, Daily Bag Limit.

In the fall of 1997, the Fishery Division established a committee comprised of biologists and hatchery staff to revisit the prospect of a rainbow trout stocking program. After deliberation of the pros and cons, the committee concluded to move forward with a limited, experimental program to evaluate the relative performance of rainbow trout, brown trout, and brook trout. While some people contend rainbows would provide angling diversity, our intentions were to determine if rainbows could provide fishery managers with an additional tool to improve fishing opportunities for Maine anglers. The study was conducted over a 5-6 year period in a variety of Maine waters and included three parts: (1) hatchery performance comparisons among all three species, (2) field performance comparisons of browns and rainbows, and (3) field performance comparisons of brookies and rainbows. A federal hatchery in Tennessee provided Eagle Lake Strain rainbow eggs used during the study.

The study is finally winding down, a draft report for part one and two has been completed. The results of the brown trout/rainbow trout field comparison were highlighted in last winter in a similar article. A draft report for the brook trout/rainbow trout comparisons is currently being reviewed, and a final report is expected to be out by this summer. Highlights from the 3rd and final report are presented in the remainder of this article.

This portion of the study evaluated the relative field performance of Eagle Lake strain rainbow trout and Maine Hatchery strain brook trout in four small, trout ponds including: Jaybird Pond (Hiram), Lily Pond (New Gloucester), Long Pond (Denmark), and Overset Pond (Greenwood). Study objectives were: (1) to compare angler catch/harvest rates and examine whether the two trout species differ in their seasonal availability to the angler; (2) to evaluate relative size and growth, (3) to assess survival and carry-over potential; (4) to compare their utilization of the food chain, and (5) to examine trout performance in waters with marginal summer water quality under different levels of competitions/predation.

Catch and Harvest Rates… Across all waters, legal-sized rainbow trout were caught and harvested at rates 2.5 and 3.8 times greater than brook trout, respectively. These results are not at all that surprising, rainbows were slightly larger than the brookies, and a higher proportion of rainbows were of legal-size rainbows at the time of stocking. A comparison of the combined catch of all legal and sublegal fish (all trout/hour) allows for a more standardized comparison, and addresses the size differential issue. Catch rates (all trout/hr) for individual study waters were higher for rainbow trout on three out of the four waters; however, the overall difference across all four waters was relatively small (1.2 times higher). The data suggest that full season catch rates are fairly similar between the two species.

On the other hand, a review of catch rates by early, mid and late season shows that brook trout typically provided slightly better early season angling opportunities, whereas rainbow trout yielded about 2 ½ times higher catch rates during mid and late season period.

Size Quality and Growth… Brook trout produced fisheries of lower size quality than rainbow trout. Brook trout averaged 11.2 inches long and weighed 0.62 pounds, where as rainbows averaged 14.6 inches long and weighed 1.1 pounds across all study waters. This data demonstrates that rainbow trout typically provided better fisheries in terms of size quality. However, the above data does not clarify whether or not the longer lengths and higher weights for rainbow trout are due to better growth, because the mean size differences may simply be a function of the rainbows being stocked at slightly larger sizes and demonstrating better survival.

To answer this question, the increase in growth since stocking (incremental growth) was examined, eliminating the initial size advantage at time of stocking. In addition, incremental growth data was further broken down by month to develop a monthly grow rate. The use of monthly growth rates allows fish that were sampled at different times during the study to be compared. Rainbow trout exhibited better monthly growth rates than brook trout, both in terms of length and weight. Monthly growth for rainbows was approximately 50% greater than for brook trout for both length and weight.

Holdover and Survival….Rainbow trout survival (holdover potential) exceeded brook trout on three out of the four study ponds. The annual survival estimate for rainbow trout was 2.7 times greater that brook trout (14 and 38%). Across all waters, brook trout older than 1+ comprised only 10.0% of our sample compared to 55.1% for rainbow trout. These results indicate rainbow trout are more likely to provide quality and trophy sized trout fishing opportunities than brook trout.

Diets….Fall diets of brook trout and rainbow trout were very similar, and surprisingly Eagle Lake strain rainbow trout did not appear to utilize larger, non-insect type food items (i.e. fish, mollusks, crayfish) anymore than brook trout. On the other hand, rainbow trout exhibited fewer empty stomachs and a higher volume of food/kilogram of trout. This may suggest that rainbow trout are more aggressive feeders, which could account for the higher growth rate observations.

Water Quality and Competition….Although our sample size was limited to only four ponds, collected survival and growth information suggests rainbow trout were more tolerant of competition and/or predation pressures than brook trout. For example, Lily Pond produced good numbers of holdover rainbow trout in the 14-18 inch range, despite heavy competition from largemouth bass, chain pickerel, black crappie, pumpkinseed sunfish, and several other fish species. On the other hand, we observed only a total of three brook trout during the four sampling events conducted between 2001 and 2006. Interestingly, rainbows demonstrated poorer survival to older ages in two ponds with limited water quality (Long and Jaybird Ponds), despite lower level levels of competition than Lily P. This suggests poor to marginal summer water quality conditions may be more limiting to rainbow trout performance than heavy competition.

In conclusion, our initial and most important reason for investigating rainbow trout performance was to explore their potential for improving angling opportunities for coldwater fish, particularly in marginal trout ponds and “put-and-take” stocking programs. Performance results from this study indicate rainbow trout have the potential to produce longer season fishing opportunities, better size quality fisheries, and a limited number of trophy-sized (≥ 18 inches) trout without sacrificing overall catch rates. However, as a trout, they still have their limitations and will only produce longer season “put-and-take” fisheries of slightly larger size quality in waters with extremely marginal water quality. In such cases, a brook trout stocking program may yield the same returns, except over a shorter period of time. On certain marginal waters currently managed for brook trout, the replacement of “put-and-take” brook trout stocking programs with rainbow trout could improve angling opportunities for coldwater sportfish in Maine.

Before the Department adopts a rainbow trout stocking program, all of the associated hatchery and management implications of such a program need to be considered. For example, if a brood stock were developed, additional equipment would be required to manipulate rainbow trout spawning times if a fall spawning strain is preferred. Fishery managers may need to protect spring spawning rainbow trout due to their vulnerability to anglers and poachers. If rainbow trout do not replace existing program, then the largest obstacle to overcome will probably be associated with space constraints in our existing hatchery system.

Perhaps, the most important consideration in initiating a rainbow trout stocking program is their potential to negatively impact native salmonids like brook trout and landlocked salmon. While I agree with Scott and Crossman’s statement in Fishes of Canada, “The rainbow has been one of the more successful, more appreciated, and less potential dangerous of the many attempts to introduce fish to areas beyond its natural range;” it would be irresponsible of the Department to not seriously consider the risks associated with the introduction of a non-native trout species into Maine waters. An important component of this risk assessment is the development of a sound rainbow trout stocking policy to provide assurances that important native fisheries will not be jeopardized by rainbow introductions. In addition, existing Department policies require all new stockings receive Division-wide peer review. This formal process ensures that new stocking proposals are justified. Additionally, existing policies also have an outreach component, which includes a requirement that public input be sought in response to proposed new stockings. Typical venues for this input include this newsletter, weekly fishing reports posted on the Department’s web site and in some local newspapers, sportsmen’s forums, and appearances at fish and game clubs and other groups.

-Jim Pellerin, Sebago Region Assistant Regional Fisheries Biologist, Department of Inland Fisheries and Wildlife

The Fish Ecology Lab I work in is responsible for long term population monitoring in the Logan River, Utah, which is home to an important metapopulation of Bonneville cutthroat trout.  A large part of this monitoring project involves collecting fish via electrofishing at eight different long term index sites throughout the river and its tributaries.  In the main stem of the Logan, high flows require that we use a canoe electrofishing unit and a large team of students, biologists, technicians, and volunteers. 

In order to complete the task, we rig up a canoe with a large generator, an electroshocking unit, multiple probes (anodes: +) operated by individuals, and a large cable cathode (+) hanging from the canoe.  

When the generator and shocking unit are turned on, and all probes and safety switches operating, an electric current is sent through the water between the probes and the cable hanging from the canoe.  This current causes fish nearby to turn sideways and become unable to escape the electrical field.  

A row of netters stand behind the people with probes and capture the fish that are caught in the electric current.  Fish are then transferred to the plastic tubs in the canoe, which contain cool river water oxygenated with bilge pumps. 

The individual pushing/pulling the canoe operates the master safety switch (we like to call it the ‘dead-man switch’), which has to be depressed for the unit to be shocking.  This person is responsible for watching everyone and ensuring that nobody gets zapped.  If about to stumble or reach into the water to get a fish between the rocks, a person calls out ‘off!’, upon which the switch is disabled and shocking postponed. 

After finishing shocking the site, workers quickly transfer fish to the station set up for data collection.  Here, all fish are measured and weighed, and adult fish receive individually numbered floy tags for future ID.  Some fish are saved for whirling disease testing, diet sampling and aging, and the majority are returned to the river. 

This process is repeated three times within an area enclosed by blocknets.  Fish captured on the first two runs are placed outside of the blocknets so that only new fish captured on the second and third runs.  Using the numbers of fish caught in each run, we can then calculate a capture efficiency, which we use to estimate the total population of fish within the blocked-off area (usually 200 meters).  This population estimate is expanded throughout the areas adjacent to the sampling site to provide general information about the area’s fish population, and is used to monitor trends in population dynamics over time. 

We’ll be back out the next three days completing our Logan River long-term sampling.  In addition to graduate students and technicians in our lab, we are usually assisted by a number of volunteers, along with people from the Utah Division of Wildlife Resources‘ Dedicated Hunters Program, where hunters complete fish and wildlife related conservation projects and receive additional hunting priveliges in return.  A reporter from the local newspaper will be joining us during the next couple of days as well, which we hope will shed more light on what we do in the river and why we do it.

Click Here for a description of my specific research goals on the Logan River

Tom Remington recently wrote a blog entry on sterile fish and their potential to grow faster and perform better than fertile hatchery fish, which allocate a portion of their growth potential toward reproduction.  The topic is a very interesting one, especially since sterile hatchery fish do not threaten wild populations with the potential for interbreeding and compromising genetic integrity.

Many state fish and wildlife agencies will tell you that they do not stock fish with the intent of seeing them reproduce.  The vast majority of stocking programs are either put-and-take, or put-grow-and-take, where fish are stocked with the intention of becoming part of an angler’s bag limit.  Furthermore, most waters are stocked because they cannot provide a fishery through natural reproduction.  Most agencies use regulations as a first resort to protect a fishery.  If natural reproduction simply can not keep up with angling pressure regardless of regulations, a stocking program is usually implemented.  This lack in natural reproduction is often due to lack of spawning habitat, but can result from other causes as well.

The bottom line is this: if most fish are stocked without the intent of reproducing, what drawbacks are there to a sterile fish that has the potential to grow faster?  I don’t see many.  Convincing the public that it’s a good idea to stock sterile fish might be a tough sell, simply because most people still don’t quite understand why a department would stock fish without expecting them to reproduce.

One of the greatest benefits to a stocking sterile fish, in my opinion, is the ability to stock these fish in waters that contain native fish that might otherwise be threatened with interbreeding or hybridization.  This means that states can stock wild trout waters with hatchery trout, knowing that they are not compromising the genetics of wild fish. 

Granted, you can’t just go willy nilly stocking on top of native fish everywhere you go.  There are issues in some areas where hatchery fish could potentially outcompete wild fish.  There are some areas where stocking is not necessary and might hinder a wild fishery in recovery.  Also, the method of sterilization, while significantly developed in some areas, is not yet foolproof.

The Idaho Department of Fish and Game has been working on producing sterile triploid hatchery fish for years, and to date, every rainbow trout stocked in the state of Idaho is sterile.  Therefore, the department has the freedom to stock in areas where they might otherwise have to worry about hatchery rainbows interbreeding with wild rainbows and hybridizing cutthroat trout populations. 

Sterilization of hatchery fish is an advancement led by state fish and wildlife agencies primarily in the West.  Idaho Fish and Game fisheries biologist Joe Kozfkay and others completed a survey of state fish and wildlife agencies throughout the U.S., and found that 10 other states have current sterilization programs, and most are in the West.  Only 2 states with fish sterilization programs lie east of the Mississippi River.

While there are some hurdles to overcome, primarily the logistics of developing a sterilization program and having state agency and public support, I believe that the future is promising and many developments lie ahead.  Because of the ever-increasing concern over the protection of native and wild fish, it is imperative that state agencies at least consider the development of a sterilization program.  Aside from it likely being mandated in the future, such a program would vastly increase the options that state fish and wildlife agencies have in relation to where they stock fish.