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The Impact of Fishing for Nesting Smallmouth Bass

Bill Schultz

Within the smallmouth bass and largemouth bass fishing communities, there’s an ongoing discussion as to whether a person should or shouldn’t fish for bass while they’re guarding a nest. When I returned to fishing in 1992, I quickly realized that fishing for male bass guarding a nest wasn’t as exciting as making that long cast and the excitement of an explosive hit, which in my case would be a smallie. Not knowing the facts, which I now do, it seemed important to leave that male alone to complete its parenting.

To find the most scientific information for this article and to confirm my own observations, I reached out to David P. Philipp, PhD, Chair of the Board, Fisheries Conservation Foundation. He is also principal Scientist/Professor, Emeritus, Illinois Natural History Survey and Institute of Natural Resources Sustainability, University of Illinois. Dr. Philipp has written or co-authored 85 peer-reviewed articles and two books on bass since 1979. When you consider that he has led over 100, with several on smallmouth bass, I feel he is someone who truly can answer the question, should we be fishing for nesting bass and what’s the impact?
I had the pleasure of spending time on the phone with Dr. Philipp and posing several questions for this article.

Schultz: When we talk northern smallmouth bass above what line geographically are, we talking about?
Philipp: The designation “northern smallmouth bass” is a classification based upon work dating many years ago. Currently, new DNA technology is revamping the classification of all black basses with 12-15 different species recognized by the scientific community. There may be as many as three minor subspecies of smallmouth bass in areas of Missouri, Oklahoma, and Arkansas, but the huge bulk of the smallmouth, from Georgia to Ontario are all northern smallmouth bass. So, there really is no geographic line.

Schultz: What happens when a bass is angled off his nest?

Philipp: To answer that, we need to understand the fascinating and complex life history of smallmouth bass. In the spring, when water temperatures reach about 12C (55F), male smallmouth move into the shallows and build a nest by fanning out a depression in the substrate, usually gravel, with his tail to clear the area of all silt. Those nests can be as shallow as 1 ft. or over 20 ft. deep. At that time, female bass cruise the shorelines assessing the males that are on nests hoping to spawn. Males actively court the females, but each female makes the actual decision on which male she spawns with. For that, she enters the nest and the two rotate side by side with her rolling onto her side every so often to extrude a small batch of eggs that he fertilizes by extruding a small amount of sperm. The fertilized eggs then stick to the rocks in the nest. That spawning activity can last from 1-6 hours at which time the female leaves the nesting area to resume feeding and to potentially spawn again with a different male a day or two later.

The male is left alone to provide the parental care for the offspring, which involves fanning the eggs until they hatch in 2-4 days depending on the water temperature. They then guard the larvae and fry for a total of 4-6 weeks post fertilization, until the baby bass reach independence, i.e., when they can recognize predators like bluegills and perch to avoid them, which is when they are about 1-1.5 inches long.

The survival of those babies depends on the guarding activity of the male parent. Without the male present, brood predators consume about half the offspring in the first 8-10 minutes and continue until all the offspring are eaten. A small number, usually less than 10 percent, of nest-guarding males choose to abandon the broods early on their own, due to sickness, injury or maybe they just didn’t get very many eggs spawned in their nest. They decide to not spend the energy trying to raise that brood, but instead to try another time or in in many instances wait until the next year. Most male smallmouth bass, however, left undisturbed, provide full parental care for their offspring, raising up to several thousand independent fry, the huge bulk of which die before they reach adulthood, a normal phenomenon. Otherwise with that level of exponential growth, there would be more smallmouth bass than water in the lake.
So, back to the question, what happens when a bass is angled off his nest? Shortly after the male is removed from the nest brood predators enter it and begin to consume the eggs/larvae. Numbers of predators increase the longer the male is off the nest until the nest is packed with small fish eating the offspring. If that male is harvested, or in the case of tournaments put into a livewell until released after the weigh-in or when culled later when a larger fish is caught, then all of its offspring are consumed, usually in less than an hour. If, however, that male is released back into the lake right after being caught, he returns to the nest and attempts to eject the predators, which depends both on the number of predators and his stamina after having been caught. If he is successful at doing that, he then assesses the status of his brood. If there are a substantive number still left, then he resumes parental care activities. If, on the other hand, there are not enough offspring to make it worth him taking the energy to finish the parental care duty, he abandons that brood to “fight another day” and his reproductive success with that brood is zero.

This description of what happens when bass are angled off their nests has been confirmed by many different research studies, scientists and is not under any contention whatsoever.

Schultz: Does angling nesting bass hurt the population as a whole?

Philipp: This is where biologists disagree. Traditional thinking is that because bass spawning is heavily impacted by environmental factors, which it is, bass recruitment. This is the annual production of a year class, usually measured as the relative number of one-year old’s and does not depend on the amount of reproductive success in the bass population, because some compensation mechanism keeps replenishing it.

Our hypothesis is radically different from that, stating that even though bass spawning is heavily impacted by environmental factors, bass recruitment depends directly on the degree of successful bass reproduction. As a result, any disturbance, including harvest or even catch-and-release angling, that causes brood loss through predation and/or nest abandonment results in a reduction in annual recruitment. Our hypothesis depends on there being a direct relationship between the lake-wide level of bass reproductive success and the resultant strength of the year class.

Schultz: Has there been any research on this and if so, what does it tell us?

Philipp: Surprisingly, given the extent of the debate and how much is riding on the outcome, there have not been that many publications on this issue. It is likely due to the difficulty in quantifying reproductive success and the time needed for studies to address the question. There have been several studies routinely cited over and over that claim to document that angling for nesting bass has no negative impacts on the bass population. Other than some research done in Florida on Florida bass, a species of black bass that varies substantially from smallmouth bass. Those studies all suffer from experimental designs that were inappropriate and incapable of answering the question because they never actually measured any reproductive metrics, much less quantified annual reproductive success and in many cases did not even measure annual recruitment.

Studies by an excellent research team out of the University of Florida have indicated that the story is more complicated for Florida bass, because the duration of the egg-laying season for this species in Florida can be as long as 5-6 months, whereas the typical duration for egg-laying in our smallmouth bass study populations are often as short as 7-8 days. So, outside of Florida there is no evidence supporting the traditional hypothesis that calls for some unknown compensatory mechanism that somehow sustains annual recruitment in the face of decreased reproductive success.

Our research group has just completed several long-term studies directly addressing aspects of this question and we are currently preparing these manuscripts for publication.

Schultz: Is there a relationship between bass reproductive success and annual recruitment?

Philipp: To answer this question we embarked on a long-term study in which we annually conducted snorkel surveys throughout the entire bass reproductive period from egg laid through the end when the last male stopped parental care. For 22-28 years in three different waterbodies in southeastern Ontario, a smallmouth lake and river, plus a lake dominated by largemouth. Every 3-4 days swimmers swam the shorelines mapping all the bass nests and recording species, total length, depth, spawning date, and scored mating success by numbers of eggs/fry. We followed every nest through to completion, determining if they were successful in raising independent fry or not. We then summed the number of fry produced in all the successful nests for that year, therein calculating the absolute number of fry produced in that year for that waterbody, its reproductive success.

To determine the level of recruitment for that year class, we snorkeled the entire shoreline 8-10 times during July and August of the next year counting the number of one-year old’s, therein calculating the relative recruitment or year class strength for that year. Each year had a point on the graph of reproductive success vs recruitment. The result for all three waterbodies showed that the annual recruitment in these bass populations depended directly on the amount of reproductive success, each with an extremely high coefficient of correlation. So, the answer to this research question is yes.

Schultz: Can angling nesting bass, even catch-and-release, actual have a big enough impact to reduce recruitment?

Philipp: We established a 12-year project on four private lakes where we could control all access and fishing activity, including instituting different management options. In randomly alternating years, each lake had one of two management scenarios. One was no fishing of any kind during the bass spawning season, the second allowed fishing that targeted nesting bass with only artificial lures, but mandated immediate release upon capture of all fish. Anglers were experienced and included our research team. To assess the resulting levels of recruitment for each spawning year, snorkelers swam the entire shoreline multiple times and counted the number of one-year old bass.

The results were so clear that we stopped the study to write it up after only eight years. In each of the four lakes, the recruitment during every year where there was no angling allowed during the spawning season was significantly greater than in years where immediate catch-and-release angling for nesting bass was allowed. Across all four lakes, the average decrease in recruitment was at least 50.

Schultz: What effect does this angling for nesting bass having on bass populations?

Philipp: First, the size of the impact certainly is dependent on the level of preseason angling on the lake. We have data from Opinicon Lake in southeastern Ontario, where there is a reasonable amount of pressure on the bass, including on nesting bass before the closed season is officially listed. Compared to other lakes in the south and Midwest where there are no closed seasons, the pressure on Opinicon Lake is comparably low. Our research over the past 28 years on this lake says that the impact is substantial.

We have monitored the reproductive metrics via snorkeling surveys in Opinicon Lake since 1990. We found between 1990 and 2000, the reproductive metrics across our study sites in the lake remained reasonably consistent, but since then, things have changed substantially. The number of nests with eggs, an indication of the number of adult males in the population, has decreased by about 30 %. The number of eggs spawned in those nests, an indication of the number of adult females in the population, has likewise decreased by about 30 %.

We also found the success rate of males that spawned and continued parental care until the end and independent fry decreased even more dropping about 40%. The absolute number of independent offspring produced in successful nests has decreased more than 40%. The numbers of one-year old bass observed and counted during the summer after the spawning year on Opinicon Lake has decreased by about half.

Those trends are quite alarming, so what is causing them? One thing that we also did during our snorkeling surveys of bass nests was to quantify the number hook-wounds that showed up on the nesters during the nesting period.

The percent of nesting male bass with hook-wounds has more than tripled over the last two decades and we estimate that in 2019 with a substantial fishing season each male bass was hooked and released between three and four times! The 2019 year-class was by far the lowest over the 30-year history of the study. Interestingly, during 2020, the year of the COVID pandemic, a year in which tourism was almost non-existent during May and June, hook-wounding was also non-existent and reproductive success was extremely high. In fact, because of the huge numbers of young-of-the-year we observed last summer, something we have not seen before over the last 30 years of snorkeling, we expect that the 2020 year class will be the largest that we have ever recorded since 1990.

Schultz: What kind of reactions have you received from recreational anglers, tournament anglers, Departments of Natural Resources, etc.?

Philipp: To be honest, most people do not want to hear this, especially those in management positions or those that are dependent on tourist dollars. We have sometimes been characterized as anti-fishing. Anyone who knows me, and my extended research group knows that we are far from that! Personally, I fish 100 days a year. Every member of our team is passionate about protecting the long-term health of our fisheries that depend on the long-term health of our fish populations. I also have found that almost to a person every angler feels that way too. Confusion and misinformation hurt our cause, particularly when it comes down to weighing short-term economic benefits versus long-term resource and eventually economic losses.

Schultz: Have you had any resistance from any other, knowledgeable researchers, such as those tied-in with bass tournaments?

Philipp: Bass tournaments that use a weigh-in at the end of the day and are held during the bass reproductive period pose a particular problem. Every male bass taken off a nest that is brought into the boat, to be weighed in or is culled later, has its reproductive success crushed to zero. Professional anglers like all bass anglers need to become more knowledgeable about the biology and take a definitive stand for better conservation of our fisheries resources. I am very excited with the immediate release format for kayak tournaments and Major League fishing with the

To be clear, I don’t want to imply that every bass lake that has any fishing pressure is experiencing a recruitment problem. We simply do not know how extensive that situation is because recruitment is only being realistically assessed in a very small subset of our bass fisheries. I I like to ask the question, if there are no issues with bass recruitment, then why are there so many bass hatcheries in every one of the lower 48 states? I also want to acknowledge that bass do not represent the angling target for all lakes and rivers, so conserving or improving the bass populations in all instances is not an appropriate goal.

What we are proposing is that for situations like Opinicon Lake we studied in Ontario that are important bass fisheries and where angling nesting bass is negatively impacting the bass populations, we should admit that the current regulations are not working. In the case of Ontario, the closed season for bass is not protecting any of the adult spawners in the lake. As a result, that ineffective regulation should be replaced with something that works, like using bass spawning sanctuaries, i.e., areas within the lake in which no angling of any kind is allowed until after the bass reproductive season has been completed. That way, at least some reasonable level of reproductive success can be guaranteed. In Opinicon, for example, protecting certain areas that amount to about 30% of the shoreline could protect over 60% of the nesting largemouth and over 80% of the nesting smallmouth. An interesting twist to negate any sense that this regulation is reducing fishing options, the rest of the lake could be open to legal catch-and-release fishing for bass, a win-win both for the bass and for the legal anglers.

There have been other studies that looked at the impact of nest fishing for smallmouth bass and how it impacts recruitment. Most concurred with or partially concurred with the seminal work by Dr. Philipp and his team who have conducted more studies over more years than any other group. Hopefully, after reading this article many who do fish for nesting smallmouth bass will give it more thought and change their strategy.

I spend a good deal of my fishing chasing smallies on the clear waters of Green Bay and Lake Michigan in Door County. I was very excited to learn recently that Dan Isermann and Greg Sass have submitted for funding a study proposal titled: Understanding smallmouth bass recruitment in relation to nest fishing along Wisconsin’s Door Peninsula. Isermann is Leader, USGS, Wisconsin Cooperative Fishery Unit, University of Wisconsin-Stevens Point. Sass is Fisheries Research Leader, Wisconsin Department of Natural Resources.