Thursday, May 16, 2013

How Hard Can it Really be to Count Fish? - Fisheries Dependent Data Collection

Photo: NOAA
It’s hard to count fish. Not only do they move, but they are hidden from plain sight within the depths of the ocean. To complicate things, an overwhelming number of variables like weather, tide, and habitat make straightforward data collection difficult and test the limitations of gear and technology.  

Fisheries science is just as complex and multifaceted as the subject it studies. Biology, ecology, oceanography, population dynamics, economics, and sociology are all woven together to create the discipline of fisheries science, which formulates our understanding of fisheries and informs fisheries management decisions.

Photo: LA Seafood
There are two very general categories of data that are used in tandem by fisheries scientists to assess fish stocks. The first is fisheries independent data in which scientists use a variety of different sampling techniques like netting, trapping, and direct observation to collect fisheries information. The second is fisheries dependent data, which relies on fishing activity and is collected with the help of professional and recreational fishermen.

Fisheries dependent data collected from commercial and recreational anglers plays an important role in determining the status of fish stocks. Harvest, especially as it relates to the amount of fishing effort, can help fisheries scientists identify trends in fish populations over time. Fisheries dependent data is also used to predict and monitor harvest during a fishing year. This is particularly important for species that are managed with a quota.  Fishing seasons are set based on past trends of fishing activity, and in-season monitoring of fishing activity prevents overfishing of a stock by tracking harvest so a sector can close when a quota is met.

Photo: NOAA
Commercial Data Collection
In the Gulf of Mexico, fisheries dependent data is fairly easily and accurately collected from commercial fishermen, in part because there are fewer than 900 commercial reef fish vessels Gulf-wide. Also, the commercial Individual Fishing Quota (IFQ) Program, a management tool used to constrain the commercial harvest of certain fish species, created requirements that have improved data collection among the commercial fishing sector. The following is a list and brief description of the fisheries dependent data collection techniques used in the commercial fishery that contribute to stock assessments. 

Onboard Observers - NOAA fisheries personnel ride along to observe fishing activities on about 1% of all commercial fishing trips. The vessels are randomly selected for participation and observations are conducted in all seasons, around the Gulf, aboard vessels using each type of fishing gear.

Logbooks - All commercial reef fish fishermen are required to document their effort and catch for each fishing trip.  A random 20% of all the commercial fishermen are also required to fill out logbooks detailing their dead discards. Ten percent of al logbooks are audited by NOAA Fisheries.

Vessel Monitoring - Commercial reef fish vessels participating in the IFQ program must be equipped with a tracking device (vessel monitoring system) that is active at all times. The vessels are also required to notify NOAA Fisheries before departing on a trip and 3 hours before the boat returns to shore.

Electronic Reporting and Trip Tickets - Commercial fishing vessels in the IFQ program must report their catch before the boat reaches shore.  Once the boat lands, the fish dealers purchasing fish harvested under the IFQ program must enter data about the price, amount, and species of fish purchased.

Dockside Monitoring - Interviews are conducted by dockside monitors who collect information on species, size, age, and fishing effort from commercial fishermen returning from fishing trips.

Photo: Emily Muehlstein
Recreational Data Collection
The recreational fishing sector includes both private fishermen and fisherman on for-hire trips. The for-hire component of the fishery is fairly easy to track because, like the commercial fishermen, the universe of participating vessels is relatively small and well known.

Unfortunately, the collection of private recreational fishing data is more complicated because the universe of recreational fishermen and their fishing effort is hard to define, and tracking the activity and harvest of an estimated 4,500,000 people participating in the fishery is not practical.  

Photo: iStock
Why is it hard to figure out how much recreational fishing there is?
Many people assume that recreational fishing effort can be quantified by simply counting fishing licenses. Unfortunately, it’s more complicated for private recreational anglers.  For starters, not all fishermen are required to be licensed; in many states, you don’t need a license if you’re over 60 or under 16.  Also, licenses don’t distinguish between fishermen targeting federal species and fishermen targeting state managed species.  Finally, some fishermen fish frequently and some fish only on rare occasions; the actual fishing effort of different anglers cannot be estimated based on possession of a license. 

Luckily, there is a surprisingly simple way to determine what the private recreational sector is catching on average:  Fishing Effort x Catch = Harvest. A national program called the Marine RecreationalInformation Program (MRIP) is used to collect information on average effort and average catch of anglers.  Since it’s not practical to ask every private recreational angler what they’ve caught each time they go fishing, fisheries scientists use a sample of the entire population to estimate the activity of the entire fishery. Fishing effort is determined using phone surveys, and average catch is determined using dockside intercept surveys. 

Photo: Emily Muehlstein
Phone Surveys - In 2012, the number of phone surveys completed in the coastal areas the Gulf states totaled 52,741. The phone survey asks people how many times they fished during a specific time period. Fishing effort is then calculated based on those responses.

Dockside Intercept Surveys - Surveyors from Natural Resources Department of each Gulf state determine the typical catch of a recreational fishing trip by interviewing people when they return from a fishing trip. The surveyors count and measure the fish that are landed. In 2012, there were 26,296 interviews conducted on the Gulf coast of Florida, Alabama, Mississippi, and Louisiana. Texas uses their own creel survey to determine recreational harvest in their state, and reports that information to NOAA Fisheries for use in stock assessments and quota monitoring.

Photo: Mike Jennings
The recreational data collection system has been criticized because it relies on a sample to determine the behavior of the entire population.  At this point, there is no way to get information about the activity of every single private recreational fisherman, so the program focuses on ensuring that the sample they take represents the entire population of fishermen as closely as possible. 

The Council, NOAA Fisheries, and many other organizations are working to find new, innovative ways to improve the accuracy of private recreational angler data. Self-reported angler information, offshore fishing permits, electronic logbooks, and many other methods are being considered as ways to enhance the current data collection system. While improved fisheries dependent data will contribute to more accurate stock assessments and quota monitoring, it will never paint the entire picture of what’s going on beneath the waves.

A full understanding of fish stocks requires scientist to directly study the fish and collecting fisheries independent data. The next installment of this series “How Hard Can it Really be to Count Fish?” will provide a more vivid understanding of fish science by describing the work that fisheries scientists are doing on the water to assess fish stocks through scientific studies of the fish themselves.