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A Six‐Decade Portrait of Florida Marine Fisheries via Landings‐Based Trophodynamic Indicators
Author(s) -
Munyandorero Joseph,
Guenther Cameron B.
Publication year - 2010
Publication title -
north american journal of fisheries management
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.587
H-Index - 72
eISSN - 1548-8675
pISSN - 0275-5947
DOI - 10.1577/m08-202.1
Subject(s) - fishery , fishing , pelagic zone , trophic level , commercial fishing , environmental science , recreational fishing , apex predator , geography , oceanography , ecology , biology , geology
Abstract Four trophic‐level (TL)‐based metrics—landings trophic spectra (LTS), landings proportions of TL categories (LP), landings mean TL (MTL), and fishing‐in‐balance index (FiB)—are used to describe Florida's coast‐specific and statewide commercial, recreational, and combined marine fisheries and to examine whether “fishing down the marine food web” (FDMFW) occurred during 1950–2007. Effects of environment‐dependent species, large pelagic species, market and exploitation pressures, and revenue on these metrics are also examined. For the commercial and combined landings, analyses indicate (1) significant shifts of LTS from lower to higher TLs; (2) significant declines of LP for lower‐TL species (2.0 ≤ TL < 3.0) and increases of LP for intermediate‐TL animals (3.0 ≤ TL < 4.2; Gulf of Mexico coast and whole state) and top predators (TL ≥ 4.2; Atlantic coast and whole state); (3) significant increase of MTL; and (4) increase of FiB during the 1960s–1980s (expanding fisheries) and significant declines thereafter (fisheries contractions). Such metrics for the recreational landings vary without trends, and the commercial metrics drive the combined ones. Commercial and combined FiBs highlight the late 1970s–mid‐1980s as a backward‐bending period characterized by declines of commercial and combined landings along with increasing MTL. Base MTLs derived for all species (groups) do not reveal any FDMFW symptoms, and use of a cutoff TL of 3.25 and exclusion of large pelagic species do not alter combined FiB. The former process maintains the increasing trend of combined MTL on the Atlantic coast and leads to stability of Gulf coast and statewide combined MTL. The evolution of economic and regulatory conditions emerges as a key factor that influenced the changes in landings trophic structure. The fisheries contractions accompanied by the reduction in landings are incompatible with an increase in exvessel price rate and revenue. Contractions in the fisheries were likely due to reduction of fishing pressure, unaccounted discards, and closed areas and seasons, which themselves were rooted in management regulations.