A Captains Guide to Understanding Fishery Stock Assessments in the Gulf of Mexico in 2012
The first thing we fishermen have to realize is that times are changing and populations are expanding toward our nation’s coastlines. With an increase in coastal populations, comes the demand for access to our Gulf of Mexico waters and the fish that live in them. One of the most popular activities people can do along our massive Gulf of Mexico coastline is go fishing. Whether you own your own boat or use charter boats, there is a way to participate in saltwater angling. The problem that fishermen face is simply too many anglers and not enough fish to go around.
Over the past 40 years, I have enjoyed fishing the Gulf of Mexico, but I wanted to understand why our fish stocks are reportedly being over capitalized? I wanted to better understand why the red snapper biomass is now reportedly growing, but federal regulators will not open the floodgates and allow us to “catch them like we used too.” I wanted to understand why trigger fish and greater amberjack are reportedly undergoing over fishing. As an angler and business owner, I want to be part of the solution instead of being part of the problem.
One reason for writing this article is because of the recent January/February 2012 Gulf Council Meeting held in Mobile, Alabama. There was a lot of pressure from the Environmental Community, Louisiana Department of Conservation and a lot of private Recreational anglers, to raise the size limit of the greater amberjack to 36 inches fork length and open the season during the months of June and July. There were arguments from the scientific community that said “the amberjack fishery will never recover to its fullest unless we allow the fish to reach maximum spawning potential at 36 inches fork length.” There were also a lot of recreational anglers that wanted the season open during the summer months so they could have the best weather and access to the fish during warmer months. They wanted to close the season during April and May, which is the time these fish spawn. The problem with closing the season during April and May is there is not much fishing pressure at that time and there is a potential to overfish the stock in the summer. So, closing the season would only be a good gesture and not much benefit to the fish. The problem with science, is it does not take into consideration that there is so much fishing pressure during the hot summer months that a lot of the fish smaller than 36 inches will be caught and released and will most likely not survive. All I know is, "Dead Fish Don’t Spawn" and if NOAA Fisheries opened the season during the summer months and raised the size limit to 36 inches, there would catastrophic negative impacts on the already stressed fishery. Under the current fishery management plan, the 30 inch fork length and the season being closed during June and July 2011 allowed the fish to recover. We came in at 76% of quota in 2011, which means the fishery can recover if we remain at status quo and leave the season and bag limits as they currently are.
The gray triggerfish preliminary stock assessment was another hot topic. The recent SSC (Statistical and Science Committee) met in January and told everyone that triggerfish was in trouble. When we heard about this, we looked at the data and found out that the updated stock assessment had some errors in it that needed to be addressed. In 2008, anglers went from a 12 inch total length to a 14 inch fork length size limit. We also went from using “J” hooks and were required to use circle hooks. This information on size limit and gear used was not taken into consideration during the SSC meeting. Anglers asked during public testimony at the Gulf Council Meeting, that the SSC committee please re-run the numbers and take into consideration the size increase and gear change before releasing the full stock assessment on the gray triggerfish and potentially avoid closing our season in May or June 2012.
Another factor on the horizon is the impact of the BP Oil Spill of 2010 on the fish stocks. The scheduled 2013 red snapper stock assessment currently will not include any information on the health of the fishery after the oil spill. The information used in the scheduled stock assessment was collected prior to the spill. That means the fish that were harmed by the spill will not have any impact on the red snapper assessment until possibly 6 years later or 2019. That is scary for all stakeholders. What happens to us fishermen if we have a fishery collapse like Valdez, Ak? It was 4 years after the Exxon Valdez oil spill before the Herring population collapsed and never recovered. It is important that you understand these things about how stock assessments can affect fisheries now and in the future.
As you can see, there are a lot of factors that go into stock assessments. It is extremely important for anglers to become engaged in the fishery management process. If it were not from my being engaged with the Gulf Council meetings, I would have never known how to recognize and try and correct issues occurring with greater amberjack and the gray triggerfish. I encourage you to read all you can and learn about your fishery so you can be part of the solution.
This article is my shortened version of how we fishermen can better understand why the Gulf Council and NOAA Fisheries are restricting and limiting access to a public trust resource by implementing short seasons and reduced bag limits. All stakeholders and managers are mandated by the Magnuson-Stevens Act of 1976. This law protects U.S. interests in federal waters out to 200 miles from our shoreline. In 1996, Congress opened the Act and amended it by passing the Sustainable Fisheries Act, which brought attention to the reduction of bycatch and the protection of fish habitat. There are eight regional fishery management councils that advise NOAA Fisheries on management issues. Our body that represents us in the northern gulf is the Gulf Council. The Gulf Council is not a governmental organization. Its members are appointed by the coastal states governors and approved by the Secretary of Commerce. Their recommendations are forwarded to NOAA Fisheries and from there, are published in the Federal Register as law. This councils responsibility is to produce FMP’s (Fishery Management Plans) with stakeholder input. A stakeholder includes any and all people who have an interest in the fishery and its management.
Catch and Effort in the Gulf of Mexico Fishery.
One of the biggest problems stock assessment scientists have is accurately capturing and measuring recreational and commercial fishing catch and effort. Catch is best described as shore side intercepts after fishermen return to port. Biologists’ aides try and capture the number, species and the size of the fish being harvested or landed by charter for hire boats and private recreational anglers upon arrival back at the public dock. The effort is measured by telephone surveys and is an attempt to find out how many fishing trips were taken during a particular reporting period. One of the biggest problems aides have is collecting information from private boat owners that return to their private docks and are never surveyed about their catch. It is those people that cause for a lot of uncertainty in fish stocks and fishery management.
Fishery managers make their decisions based on a long but continuous cycle of collecting information. Some components of this cycle include collecting data, assessing fishery health, setting catch targets and making fishery regulations. The goal is to ensure all fisheries remain sustainable for years to come.
Before we go any further, I wanted you to understand that stock assessments are vitally important in fishery management. Even though economic times are tough and fishing regulations are strict, we must remember that in order to improve things, we must first understand what we are trying to accomplish. Fishermen want longer seasons and increased bag limits and fishery managers want a healthy, viable and sustainable fishery that will be productive in the future. There is a solution somewhere in the middle for managers and stakeholders.
In order to get started, I thought it is important to start explaining a few things to get the ball rolling so we all have a better understanding of fishery stock assessments. We first need to give you a couple of definitions that will help you understand what we are talking about.
A fish population – is a group of individual fish that interbreed that live in a given area. This area can be as small is Mobile Bay or as large as the State of Alabama’s artificial reef program area. It can also be as large as the entire Gulf of Mexico.
A fish stock on the other hand, is defined by management concerns. This concern can be over jurisdictional boundaries like Texas and Florida having nine miles of offshore water to fish and Alabama, Mississippi and Louisiana only have three miles of state water. Fish stocks can also be managed by harvesting locations and by biological reasons. Inside the fish population and the fish stock, is what is called a cohort or year class of fish.
A year Class is fish born at the same time of a year. Gulf of Mexico Fishery Managers call this a recruitment class. Having an annual year class of red snapper born in the Gulf of Mexico is extremely important to the rebuilding plan of the biomass of the fish. The size of the year class has an impact on future fishing seasons. Currently, there is an estimated 100 million pounds of Red Snapper Biomass in the Gulf of Mexico, but we are only allowed to harvest just over 8 mp of it in 2012. That is why stakeholders are angry and want longer seasons. With 100 mp of Red Snapper, why can we only harvest 8 mp per year? That is why it is important to understand what sustainable means. That definition will come later in this article.
What a Gulf of Mexico Fishery stock assessment is:
What a lot of fishermen don’t realize about stock assessments is that they are designed to protect the interest of all stakeholders. Their goal is to maintain healthy fish populations, a healthy charter and commercial fishing industry and recreational anglers’ interests. The fishery managers and science and statistical teams use all kinds of tools to accomplish their objectives. They use fish quotas, bag limits, size limits, fishing gear and tackle restrictions, fishing season timings and area closures as ways to manage the fishery.
Stock assessments tell the history of the fishery stock and the current status of it. They ask questions like, “Is the fish stock growing? Is the fish stock declining?” Scientists also try and figure out things like “If fishing pressure is increased on a certain species, how it will affect next year’s stock or five years from now’s stock?” The objective is for fishery managers to interpret all of the information obtained and decide which management options are best. A stock assessment also describes the life history characteristics for a specific species such as age, growth, sexual maturity, reproduction, mortality, environmental factors (like the BP oil spill in 2010), feeding habits and geographical boundaries of the fish stock and population.
Complete stock assessments have a lot of information on both the fish population and the entire Gulf of Mexico Fishery. Stock assessments depend on fishermen and scientists, both to give qualitative and quantitative descriptions of the fishery for a specific species. This information comes from the past information taken and present information gathered.
Scientist use what is called an assessment model, which are mathematical and statistical methods to perform their stock assessments. This model is what fishermen don’t understand because it does not always reflect what fishermen are actually seeing in the fishery. An example – Currently, red snapper in the Gulf of Mexico are everywhere. You can hardly catch any other fish without stepping on the heads of Red Snapper. What a lot of people don’t want to admit, is that until 2006, fishermen had a hard time finding legal size 16” red snapper on any public reef off the Alabama coastline. The big question today from fishermen is “Why can’t we catch Red Snapper, they are everywhere?” What a lot of anglers fail to understand is that we are in a rebuilding plan in the Gulf of Mexico and even though there are an abundance of red snapper from one to seven years of age, there is not an abundance of fish from eight years of age up to forty years of age. Where did all the old red snappers go? Most of them went north in coolers because of years of over fishing. Orange Beach, Alabama alone was responsible at one time for harvesting 46% of the TAC (total allowable catch) of the recreational red snapper each year. Simply put, we were catching fish faster than they could reproduce.
Types of fishery data collected by stock assessments
Fishery data is broken down into two categories. There is fishery dependent data and fishery independent data. Both are critical in obtaining accurate stock assessments.
Fishery Dependent Data is information collected from the actual commercial and recreational fishing process and is collected through self reporting, dock side surveys, telephone surveys, on board observers and vessel monitoring systems (VMS). At this time, only commercial fishing boats have VMS’s on board.
This type of data depends on landing records of fish or what is called port side sampling. The information is collected on landed fish. The sampler weighs the fish and rarely uses the total number of fish caught. Weight is more important than number of fish harvested. The sampler also collects additional data by doing a creel survey. A creel survey is where the person takes otolith (ear bone) samples from fish to help age the fish. This is where they count the rings on the ear bone which is similar to measuring the growth of a pine tree by measuring the growth rings. Information and tissue samples are taken back to the lab where scientist performs additional studies of the fish. If scientists take age and size samples from a large number of fish, they can better estimate the age of the fish based on length. By doing this, it is easier for scientists to convert the length distribution on caught and landed fish into age distribution of the same. However, after the BP oil spill, fishermen are catching some fish that are thinner than they used to be. The stakeholders asked the Gulf Council to collect a new survey of fish and find out if the weight changed in the formula? What happens if a 22 inch red snapper weighed 7 pounds prior to the Oil Spill, but now only weighs 6.5 pounds? How much weight would that be if fish were 1/2 pound lighter than previously recorded? What happens if they are 1/2 pound heavier than previously recorded. If the fish weighed less, it would take longer to catch the quota. If the fish were heavier per inch, it would take a lot less time to catch the quota. See my point?
Log Books or Vessel Trip Reports are types of data collection tools used in commercial fishing fleets and some charter boat surveys. They are either a requirement or voluntary in nature. These log books are a validation tool that fishermen can give to law enforcement officers at any time to ensure laws are being adhered too. Log books are better tools to use than estimating total weight and numbers of fish caught. These books are valuable because they help scientists tell where the fish were harvested and the amount of effort is in the fishery. At this time, only commercial boats or boats that have commercial quota have VMS or Vessel Monitoring Systems onboard that give fishery managers a GPS or Global Position Signal that tells where the effort in the fishery is. This simply means that fishery managers can tell where fishermen are fishing by using real time data that is overlaid over a Google Earth Map of some type.
Telephone Surveys are used as the primary method for collecting data in recreational fisheries. The current method is conducted as part of the MRFSS – Marine Recreational Fishery Statistics Survey. This method is fast being replaced in 2012 by the MRIP – Marine Recreational Fishery Program which is designed to have better flexibility in it than purely telephone surveys. At best, the telephone surveys try to estimate the number of recreational fishing trips that are taken and what species the anglers are targeting and or catching. In these surveys, the fish are categorized as caught and kept and verified by dockside sampling, caught and released.
Bycatch is where fish are caught during the fishing trip that is not necessarily targeted. It’s like fishing for Red Snapper and you end up catching gag grouper, red grouper or any other reef fish. Not all bycatch is discarded. However, bycatch is created when you have to throw back fish that are not in season, in season, the wrong sex, wrong size or even the wrong species. The Shrimping fleets have a lot of bycatch in their nets that are killed and simply shoveled overboard after they pick out the shrimp. This is another type of bycatch that effect fish stock assessments. Fish that are thrown back because of these reasons are called discards. The number of discarded fish can be bad for stock assessments.
Based on other studies that have been conducted in the past, there is a number of fish that are released that don’t survive. These released fish are called by-catch. By-catch is also where the released mortality number comes from. A perfect example of this is the Atlantic Red Snapper Fishery. Angler’s number of discarded fish that don’t survive when released is larger than the TAC (total allowable catch) of the species. If for example you are allowed to catch 1 million pounds of red snapper and the number of anglers surveyed by telephone is large enough, the number of fish released and die exceeds that 1 million pound number, then that means anglers are releasing more fish that are dead than they were allowed to harvest alive. Simply put, there are too many people fishing in the water, too many hooks and simply not enough fish. The South Atlantic Council put a rule in to stop the releasing of fish saying “you may not fish for red snapper.” That is because anglers are releasing and apparently killing more fish than are allowed to be harvested. The entire fishery is currently closed and is in a rebuilding period which means simply, giving the fish enough time to hatch, grow up and mature to where the fish stock is sustainable.
Onboard Observers are required in some fisheries. This is where the government places a person on commercial fishing boats in an effort to verify and validate how fishermen are catching fish. They collect data from the fish landed. They collect the information on the length of fish, age of fish and estimate by-catch and discarded fish.
Fishery Independent Data used in stock assessments
Fishery Independent Data is information that comes from activities that do not have anything to do with commercial or recreational fishing processes. Most Fishery Independent Data is conducted and performed by state agencies such as Alabama Marine Resources Division, Texas Parks and Wildlife, Louisiana Department of Wildlife and Fisheries, Florida Department of Conservation (FWC) and Mississippi Department of Conservation and Natural Resources. These groups of scientists take their own samples for study. They use gear like trawls, video, laser counters and seines to gather their information. These surveys can target groups of several different species or a single species of fish.
One of the key elements of collecting fishery independent data is using standardized survey practices over long periods of time. These scientists must use the same size hooks, same size nets and trawl at the same speeds to maintain the quality and comparability of their surveys. If these scientists change their gear, it is important to calibrate it so they get similar results from previous studies.
The surveys collect data that tells the fish abundance. This is where they count the number of fish caught in their nets during each tow or trawl. The information also tells them the number of each type of species, sex, length, age and stomach contents to help determine what these fish feed on. Another survey method used is fish tags. Researchers imbed fish tags in the fish and release them. When these fish are caught by anglers, there is a number that they call to report when, where and depth these fish were caught. This information helps scientist track where these fish were released after tagging and help figure out migration patterns and how much they have grown since released. All of this information helps fishery managers in setting their stock assessment models.
Biological Reference Points in Stock Assessments
A biological reference point is a number or value that scientists use for a fish stock or fish mortality. These points are used over a long period of time and serve as reference points for stock assessments. These points give fishery managers such as the Gulf Council guidance on whether fish populations is over fished or if the fish stock is too small.
Fishing mortality rate is something that is getting ready to bite a lot of us anglers in the buttocks. Simply put, this is the rate at which fish are being removed from the stock by commercial and recreational anglers. It is up to fishery managers under the advice of the Statistical Science Committee to keep fish stocks sustainable or at maximum sustainable yield (MSY). This number is designed to keep fish stocks growing without hurting the brood stock. MSY is the largest number of fish caught continuously without digging into your biomass thus hurting or reducing the fish stock.
Biomass is word we constantly hear from fishery managers about the gulf red snapper. The biomass is the total actual weight given to a particular fish stock. It is usually given in X number of million pounds for the red snapper. We also hear fishery managers talk about Spawning Stock Biomass (SSB), which is the total weight of the fish that are sexually mature and are capable of reproducing. Anglers on the other hand, always want to catch a trophy fish or what is called a cart topper.
Optimum Yield (OY) is a number in pounds that fishery scientists uses to try and determine that will give a long term yield and benefit to all of the stakeholders. Optimal yield must also take into account the biology of the fish, coastal economies and public outcry as well as environmental protection. Environmental protection includes things like the effects of the oil and dispersants put in the water during the BP Oil Spill, water salinity, water temperature, artificial and natural reef structure, predator fish, bait fish and anything else that could affect the fish stock. All of these factors have an affect on fishery managers determining the OY for the fish species that are being managed. What this means, is that anything or any circumstance which affects the birth, growth and death of a fish has to be considered by fish managers.
Fishery managers use biological reference points to help manage the fishery. In order for them to be able to measure their success, they must set targets and thresholds of what they are attempting to manage. A target is basically a number created to determine a value given for a particular fish stock. Targets are set after careful biological and socioeconomic factors are met. This is where fishery managers have to ask themselves what the OY is going to be if they set their target too high or too low. This is where fishery management policy kicks in. Currently, we are all working under that MSA (Magnuson Stevens Act) and it is the policy for which our Gulf Council is working under. The failure to adhere to red snapper targets in the past caused the fishery managers to implement what is known as Control Rules. These rules are what we are living under right now in the Gulf of Mexico. These control rules can be relaxed over time as the health of the fish stock improves. However, fishery managers are reluctant to do this because of the fear of stock uncertainty.
A threshold is a fancy word for limit. Fishery managers always try to avoid hitting their threshold or limit. This means that if a particular fishery like the Red Snapper in the Gulf of Mexico hits its limit, the potential of over fishing becomes reality. In 2011 for example, Gulf of Mexico fishermen had 48 days of Red Snapper season. During this time, anglers caught and estimated 1 million pounds of Snapper more than they were allowed. This over fishing in 2011 is likely cause the 2012 season to be cut even shorter (appox 40 days) in order for fishery managers to keep from hitting their threshold or limit. The amberjack fishery as mentioned above, is not currently undergoing over fishing and the management plan is working on this species.
Stock assessments are designed to address whether a fish stock such as red snapper is undergoing over fishing or if the fish stock is over fished. At this time, the Gulf Council says red snapper are currently undergoing over fishing. That is why the managers are going to take the season from 48 days in 2011, to potentially 40 days in 2012. Over fishing is when anglers are catching fish beyond their limit or threshold. Over fished is when a fish stock size goes below a certain limit that is either in numbers of fish or the biomass of the fish.
Stock Assessment Fishery Uncertainty
Uncertainty in fish stocks is the main reason why fishery scientists hold back a large number of fish each year in the Gulf of Mexico red snapper fishery. Because scientists can’t actually count all the fish in the Gulf of Mexico and their science is at best, between SWAG (Scientific Wild %$# Guess) and a WAG (Wild %$# Guess), fishermen suffer the consequences and have short seasons. Now, these fishery science people are very smart and their methodology is proven for the most part. It would be better if they could pull the plug and drain the Gulf of Mexico so they could actually count the fish but in the real world, it simply does not happen that way. The problem fishermen have with uncertainty is that sometimes as much as 1/3 of the Total Allowable Catch (TAC) anglers are allowed to catch is put in a fishery manager’s general ledger as being “uncertain” and not allowed to be caught. It is like a reserve account.
Fishery scientists main goal is to give numbers value in their formulas. They do this by setting numbers for the fish stock size and the mortality rate of the fish. The number assigned is called a point estimate. Point estimates are what fishery scientists call true numbers and to the best of their ability, believe in them. These numbers are the best scientists can do in estimating the current fish stock size. In contradiction to point estimates, there are vast arrays of values that create different science models. These different values also explain different science models. Uncertainty is created when scientists try to explain the reason why the ranges are so far apart. This is why the new Marine Recreational Information Program (MRIP) has come on line in 2012. It takes different models into consideration when scientists are performing stock assessments.
The problem with stock assessment models is that they create uncertainty. If a scientist ignores a lot of the uncertainties, it can lead to too much confidence and cause fishery managers make poor decisions. On the other hand, if a scientist has too many uncertainties, fishery managers may decide that the information is useless and makes them afraid to use it to make decisions. Again, it is uncertainties that cause anglers and stakeholders to suffer. The effects of the BP Oil Spill on the ecosystem and fish stocks will certainly be on the minds of the scientist for years to come. It takes a long time to fully understand the impacts on such manmade disasters. In defense of the scientists, if they allowed over fishing of a fish stock to continue, then the biomass shrinks and leaves all stakeholders in dire straits.
Predicting Next Years Gulf of Mexico Fish Population
Scientists that work on stock assessments almost always operate based on some kind of population dynamics model. However, they all look at these models differently. Dynamics models simply put a mathematical formula to fish being born, growing up, reproducing and dying. The formula’s even take into consideration whether the fish die from natural causes, from fishing effort or both.
Scientists’ goal is to try and predict how many fish are in a particular stock. They take the number of fish that think are alive and subtract those that die, and then they add the number that are born. This number should equal how many fish are going to be alive next year. It’s kind of like banking where they use debits and credits in a checking account. The population dynamics model gets really complicated for the lay person to understand. I will give you some of the terms and definitions that fishery scientists use in order to manage the fisheries.
Fecundity is the fixed number of fish that a mature fish produces and the number of offspring that will survive. This is a number that a single fish will produce. Net fecundity is the total number of new fish (recruits) that that a single fish will produce. Growth rate is derived from the relationship that Net Fucundity has with the fish’s Mortality Rate. We have all heard that our fish stocks are improving and getting bigger each year. Imagine a mortality rate of 30 percent in a fishery and the net fecundity rate is 40 percent that means the fish stock will increase by 10 percent or the growth rate is 10 percent. Scientists even take into consideration that some fish stocks will hit the upper limit of their growth rate. This limit is also called a carrying capacity.
To complicate the models even more, scientists also know that every minute of every day and night, there are fish that die naturally. It’s kind of like the human population, there is always someone dying and someone being born. They call this part of the formula – instantaneous mortality rates.
To make things more confusing for scientists, they have to take into consideration, the age of the fish. We call them age groups or year classes. Because of this part of the formula, scientists put fish into age structures. Once fish get to a certain age, scientists create another group called a plus group. This group contains fish of a certain age or older. They can even predict next years plus group each year.
Biomass of the Fish vs Individual Weight of the Fish
When talking about weight and biomass, we must first understand that fish population models mostly deal with the number of individual fish that are in a particular stock. They are categorized as an entire group or by their age. Sometimes fishery managers choose to look at the biomass of the fish stock, which is the total weight of all the fish in the stock. For example, as mentioned above, the biomass of the red snapper in the Gulf of Mexico is estimated to be 100 million pounds.
The best way for scientist to estimate the biomass of a particular fish stock is to calculate the average weight of the fish in each age class or weight for the entire stock and multiply that number by the number of individual fish in that stock. Stock assessments are purely numbers driven and those numbers are converted into weight.