Poor Jack: The Plight of a Forgotten Fish

2019 Student Writing Contest Winning Essay

Carissa Gervasi

Author Carissa Gervasi holding a Jack Crevalle captured via hook and line.

In the state of Florida, fishing is a big deal. Recreational saltwater fishing alone creates hundreds of thousands of jobs and brings in billions of dollars of revenue each year (NMFS 2017). That’s a really big deal. If this industry were to disappear, it would enact a major toll on the state economy and put a lot of people out of a job. To prevent this from happening, we need to ensure that fish populations can keep up with high levels of fishing pressure, so we don’t end up with too many anglers and not enough fish. Fisheries scientists have been working on balancing fish population growth with human demand for decades, and currently many of Florida’s important fish species are protected via a myriad of management tools.

However, there is one fish species that has been consistently ignored, despite it being extremely important! This species is a large marine fish that can grow up to 4 feet long and is a powerful swimmer with a torpedo‐shaped body. A voracious carnivore, it consumes everything in sight. Have you guessed it? This species is the Jack Crevalle Caranx hippos, commonly referred to as Jack. People love fishing for Jacks because they put up a great fight, but for some reason they are completely unregulated in Florida and in any other state along the Atlantic coast for that matter. This means there are little to no restrictions on fishing for Jacks. How did such a big, powerful fish manage to slip through the cracks? I have no idea. But what I do know is that anglers are starting to express concerns about Jack abundance (Lower Keys Guides Association, personal communication). My goal is to reveal the when, where, why, and how of Jack population decline and figure out how we can restore and conserve this important species into the future.

Figure 2. A Jack Crevalle being surgically tagged with an acoustic transmitter.

One tool I am using is key informant interviews, which are now commonly being used in science to learn about the environment (Hind 2015). Where rigorous scientific data don’t exist, as in the case of the largely ignored Jack Crevalle, local knowledge from people who have worked and lived closely linked to the environment for many years can provide critical information that we wouldn’t otherwise know. I have interviewed several fishing guides from the Lower Florida Keys who have been on the water almost every day for 10 to 39 years and all of them told me that Jack populations have declined substantially. Several suggested that it may be a combination of fishing pressure, overfishing of an important prey source, and changes in water quality that are impacting this important species. This means that management efforts to restore Jacks may need to happen at the ecosystem scale (Figure 1).

Figure 3. Map of acoustic receiver locations within three collaborative networks: the Atlantic Cooperative Telemetry Network (ACT), the Florida Atlantic Coast Telemetry network (FACT), and the Integrated Tracking of Aquatic Animals in the Gulf of Mexico network (iTAG). Credit, Lucas Griffin.

However, most guides from the Upper Florida Keys have not noticed any change in Jack populations. Does this mean the Jack decline is only a Lower Florida Keys problem? This depends largely on how much Jacks move. If Jacks exhibit long‐range migrations into different counties or even across state lines, local management only in the Lower Florida Keys may not be enough to conserve the species. To tackle this problem, I am using acoustic tags to track Jack movement patterns (Figure 2; Cooke et al. 2004). These tags emit unique ultrasonic signals that are detected by specialized receivers. Currently, thousands of receivers are sitting at the bottom of the ocean in areas throughout the Florida Keys and along the Atlantic Coast (Figure 3). These receivers “listen” for tagged animals and help us track their movement patterns. The results of this research will help us figure out if Jack management needs to occur at a local, statewide, or multi‐state scale. Humans and the environment are inextricably linked, and if we want to continue ensuring that our planet’s vital natural resources are used sustainably, scientists, stakeholders, and managers need to work together and make sure no one else important slips through the cracks.