Fisheries Management Strategies in Louisiana

According to National Marine Fisheries Service (2017) the landing of Louisiana commercial fishery is 1.2 billion pounds of fish and it is valued about $407.2 million, It also leads in blue crab, shrimp and oyster landings recognizing the primacy of shrimp fisheries in southeastern United States.

Guillory et al. (2001) reported that for a period of twenty years Louisiana has accounted for a mean value of 62 percent of the yearly landing of blue crab in the United States. The landing values of crab fisheries have been affected by hurricanes and anthropogenically induced disasters (NMFS 2017). The Terrebonne basin accounts for the highest blue crab landing in Louisiana (Bourgeois et al. 2014).  The different gear types used in Louisiana blue crab fishery are crab trap, skimmer nets, trotlines, handline, cast nets and otter trawls, although the gear used primarily for blue crab fishery in Louisiana are crab traps used with different types of baits (Guillory et al. 1996).

Shrimp fishery in Louisiana is made up the brown and white shrimp fishery (Bourgeois et al. 2016). About 43 percent of the shrimp harvested from the Gulf of Mexico(GOM) since 1963 are harvested from Louisiana waters (NMFS 2017). In Louisiana and the GOM otter-trawl is the main fish gear used in shrimp fishery, other gears include cast nets, butterfly nets and skimmer nets and the minimum mesh size allowed on these gears is 3.2mm (Bourgeois et al. 2016). Landings from the Barataria and Terrebonne basins accounts for majority of the landings of shrimps in Louisiana (Nance 2009).

The gears used in Louisiana oyster fishery are tongs, oysters and dredges (Banks et al 2016). Most of the oyster landed in Louisiana are harvested by scrapers (LDWF 2014).

Fishing gear can be classified into surrounding nets, seine nets, trawl nets, dredges, lift nets, traps, hook and lines, grappling and wounding, and harvesting gear (Nedelec and Prado 1990).

It is evident that overexploitation of marine resources is a pertinent problem in fisheries worldwide caused by increasing demand and growing world population that leads to fishing beyond sustainable yield (Myers and Worm 2003). The precision and selectivity of species and size by gears has been a major consideration in fish gear technology (Hall et al 2000). The fishing gears used for different types of fisheries have been worked upon to increase their selectively which fisherfolks hypothetically assume will increase their yields (Halliday and Pinhorn 2002). Fish populations are constantly being replenished by large sexually mature adults (Birkeland and Dayton 2005) and the depletion of these large adult fish populations through selective fishing distorts the trophic dynamics of targeted fishes (Anderson et al. 2008). Selective fishing inadvertently changes the maturation cycle of targeted fish species (Law 2000).

Bycatch is the part of a fish landing that is returned because of legal, economic and social factors (McCaughran 1992). Hall (1996) defines bycatch of fish based on their economic value and the fish survival. Utilization of proscribed fishing gear exacerbates bycatch and some gears allows for more survival of bycatch in comparison to one another (Clucas 1997). Bycatch depletes untargeted fish population, and particularly causes a decline in population of fishes placed on conservation status (Crowder and Murawski 1998), and bycatch has a significant impact on marine ecology (Kelleher 2005). Bycatch also reduces the biomass that bolsters the abundance of other fisheries and affects the trophic structure of established aquatic communities (Dayton et al. 1995).

Sea turtles, marine mammals and invertebrates are usually caught as bycatch in fishing for economic valuable species (Hall 1998). Arlinghaus et al. (2008) suggests that the size and type of bait used in fishing gears affects the mortality rate fish release because larger baits either from a natural or artificial source tend to catch larger fishes, although there might be a few exceptions in the use of natural baits. Chuenpagdee et al. (2003) grouped fishing gears in the US and ranked them based on their impacts on the habitat and the highest level of habitat impacts is caused by gears that scorch the bottom such as bottom trawls and dredges. The use of active fishing gear for harvesting bottom dwelling fish species depletes their environment (Dayton et al. 1995 add) and increased fishing effort decreases the productivity of organisms in benthic environment through uninterrupted removal of large biomass. (Kaiser et al. 2002  add).

In the catch from world oceans gregarious fish species are usually the most exploited species (FAO 1995). These species are usually exploited using different fish aggregating floating devices such as logs (Hallier 1994), light generating devices and sound manipulation (Nikoronov 1973). The combined effects of over exploitation and urbanization of areas close to the coast have led to the use of fake logs particularly in Tuna fisheries (Telleria et al. 1999).

Fish gear used in shrimp fishery in the Gulf of Mexico has a benign impact on the substrate because these substrates are impervious to the effects gears used in shrimp fishery (Sheridan and Doerr, 2007). In Crab fishery in Louisiana the crab traps have a benign impact on the benthic environment because they are mostly made of Oyster beds, but these crab traps causes bycatch of many fish species (Guillory 1993). Oysters reefs, oyster juveniles and other shelled organisms are impacted by the harvest of oyster (VanderKooy 2012). Oyster reefs provide habitat for shrimps, crabs and several finfish species (LDWF 2014). In Louisiana, Oyster reefs also helps in water purification and coastline stabilization (Piazza et al. 2005). Ghost fishing is seldom in oyster fisheries due to the use of scrapers although the use of oyster cages has increased the number of discards (Banks et al. 2016).

Ghost fishing is prevalent in Louisiana crab fishery and it is caused by abandoned or lost traps, although there are no exact figures (LDWF 2017). There are different estimates for the number of derelict traps caused by crab fishery in Louisiana (Guillory and Merrell 1993; Guillory and Perret, 1998). Abandoned crab traps exhibit size selectivity and traps large blue crab species consequently leading to their mortality (Guillory 1993). In coastal Louisiana, an abandoned crab trap captures between 2.4 to 3.5 crabs (Anderson and Alford 2014)

Harrington et al 2005 suggests that the yearly total number of discards in the US is 28% of the total 3.7 million tonnes landed, otter trawl account for 72% of these discards, and the Gulf of Mexico had the highest discard proportion to landing of 4.56. Conversely Scott-Denton et al. (2007) reported that the proportion of discards to landings in Louisiana was 0.63. Discards in shrimp fishery include finfish, crustaceans, aquatic invertebrates and debris (Bourgeois et al. 2016).

Wells et al. (2008) used red snapper to the extrapolate the selectivity of gears in the Gulf of Mexico and trawl had the highest landing and this corroborated the report of Chuenpagdee et al. (2003) that categorized landings in the Gulf of Mexico by specific gears and trawl having the highest number.

The United Nations through the Food and Agricultural Organization has sought to ameliorate bycatch by establishing codes for responsible fisheries (FAO 1995). The rate of discards estimated by the United Nations is 8% of the total landing. Although bycatch can’t be indispensable from fishing, the Magnuson Stevens Conservation Act of 1996 calls for a reduction in mortality caused by bycatch (NOAA Fisheries 1996). Practically, bycatch can be reduced by using bycatch reduction devices (Donna et al 1997 add), monitoring fishing timing, and alternating fishing methods (Morgan and Chuenpagdee 2003). Technological improvement in fisheries has sought to improve gear selectivity (Broadhurst 2008) because improved gear selectivity reduces bycatch, increases size and species selectivity thereby increasing economic value of the landing (Broadhurst 2000). Conversely this improved gear selectivity changes the dynamics of aquatics and inadvertently depletes the species being conserved or managed (Baundy et al. 2005).

There have been proponents for the utilization of bycatch for human consumption or as an alternative protein source to mitigate discards and create a feasible economic return (Peterkin, 1982).  The capture of unwanted species can also be reduced by fishing in areas known to yield modicum quantity of bycatches (Caddy 1982). The United States government has created some strategies such as the placement of a government personnel on fishing vessels to acquire data and monitor the fishing practices on board (Rasmussen and Holts 2001). In some specific locations fishing gear such as the use of bottom trawl is prohibited in some parts of the pacific (Anon 2002) and there might be complete closure of certain locations from a fishery (Caddy 1982; Collie et al. 1997). The use if an extended funnel which served as a bycatch reduction device was evaluated in Gulf of California, Mexico and it was shown that there was a 40% decrease in bycatch using this device (García-Caudillo et al. 2000).

Bycatch reduction devices are not enforced in Louisiana in state water shrimp fisheries (Bourgeois et al. 2016). The recent use of bycatch reduction devices in Louisiana shrimp fishery has been recorded and it has shown a reduction in the bycatch to landing ratio (Bourgeois et al. 2016). Using bycatch reduction devices, in 2014 the ratio of bycatch to shrimp landed was 1.94 (Scott-Denton et al. 2014), while in 2013 the ratio of discards to shrimp caught was 0.92 (Pulver et al. 2014).

The restoration of lost or destroyed oyster habitat reef in state waters by cultch planting (Banks et al. 2016)

Some management approaches in crab fishery to prevent ghost fishing include removal of abandoned crab traps, the enforcement of the utilization of visible floats and duplication of outlets for escape for non-target species (Bourgeois et al. 2014).

Guillory and Prejean (1998) showed that the use Terrapin excluding devices in crab traps reduced the capture of terrapins, it didn’t the reduce the bycatch of other species.

The use of circular hooks was sanctioned by the GMFMC to reduce bycatch and a conservation approach in reef fishery in the GOM (GMFMC 2007).

Fisheries management strategies should consider gregarious fish species that are normally in school and tend to show a strong attraction towards floating devices and thus incorporate these school behaviors in their planning (Parrish 1999). The use of ecosystem models can elucidate the relationship among fish gear selectivity, bycatch and fish mortality, these models can also help in mapping areas that often produce bycatch (Pope 1991, Rotchet et al. 2011).