Parrotfish sex ratios recover rapidly in Bermuda following a fishing ban

O’Farrell, Shay; Luckhurst, Brian E.; Box, Stephen J.; Mumby, Peter J.

doi:10.1007/s00338-015-1389-5

Cited by 15 publications

(20 citation statements)

References 21 publications

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“…This practice leads to concerns that, unlike non-sex-changing species, sperm can become the limiting factor to reproductive output if males become sufficiently rare in the population (Alonzo and Mangel, 2004a). Empirical studies have shown lifephase ratios skewed towards the female-dominated initial phase in parrotfish (Hawkins and Roberts, 2003;Molloy et al, 2011;O'Farrell et al 2015a) as well as in other species that undergo size-selective fishing (Heppell et al, 2006;Hamilton et al, 2007).…”

Section: Research Articlementioning

confidence: 99%

“…Stock-recruitment relationships are extremely difficult to establish for coral reef fish because of the influence of long-distance larval dispersal and density-dependent mortality post-larval settlement (Roberts, 1996). For example, O'Farrell et al (2015a) found no evidence that recruitment of stoplight parrotfish was related to the condition of the adult population in Bermuda, the most isolated reef system in the Western Atlantic. However, some evidence has emerged showing that recruitment is likely to be controlled at least partly by local reproduction (Schultz and Cowen, 1994;Green et al, 2015).…”

Section: Reproductionmentioning

confidence: 99%

“…Growth rate is divided by 52 to convert annual increments to weekly increments. Each fish is assigned an individualized value for maximum fork length by drawing from an empiricallyobserved distribution of L inf values, in order to reflect the variation in growth seen in nature (Choat et al, 2003;O'Farrell et al, 2015a). Growth rate of each fish is then assigned according to the following relationship between L inf and K:…”

Section: Somatic Growthmentioning

confidence: 99%

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Leveraging sex change in parrotfish to manage fished populations

Pavlowich

Webster

Kapuscinski

2018

Elementa: Science of the Anthropocene

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Healthy parrotfish (family Scaridae) communities fulfill the essential ecosystem process of herbivory in coral reefs, but artisanal fisheries that target parrotfish have degraded their populations. Outright bans and gear restrictions that do not allow parrotfish capture can effectively protect and restore parrotfish populations. As these management actions would be unfeasible in many places, options that allow some fishing but still encourage population rebuilding need to be considered. The life history of parrotfish complicates management decisions because they transition from a mostly female “initial phase” to an all-male “terminal phase.” Size-selective fishing on the largest fish can lead to unnaturally low proportions of males in a population, potentially leading to losses in reproduction. At the same time, these visually distinct life phases could present an opportunity to employ a type of catch restriction that would be easy to understand and monitor. We built an agent-based model of the stoplight parrotfish, Sparisoma viride, which included three possible mechanisms of life-phase transitioning, to predict how this species and others like it might react to catch restrictions based on life phase. We found that restricting catch to only terminal-phase (male) fish typically led to populations of greater abundance and biomass and less-disturbed life-phase ratio, compared to a similar fishing mortality applied to the whole population. This model result highlights a potentially important lesson for all exploited protogynous hermaphrodites: a robust population of initial-phase fish may be key to maximizing reproductive potential when the size at life-phase transition compensates for changes in population structure.

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Section: Research Articlementioning

confidence: 99%

Section: Reproductionmentioning

confidence: 99%

Section: Somatic Growthmentioning

confidence: 99%

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Leveraging sex change in parrotfish to manage fished populations

Pavlowich

Webster

Kapuscinski

2018

Elementa: Science of the Anthropocene

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“…Beginning in 1993, when local fishermen could no longer legally harvest parrotfish, Bermuda populations of this group of seaweed grazers rapidly increased, as did larger-sized individuals of these species (O'Farrell et al 2015(O'Farrell et al , 2016. In 1990, when the latest Bermuda fish pot ban (Burnett-Herkes and Barnes 1996, Smith-Vaniz et al 1999) was put into effect to stop the by-catch of protected species, including Yellowfin (Mycteroperca venenosa), Gag (Mycteroperca microlepis), Tiger (Mycteroperca tigris), Nassau (Epinephelus striatus) and Red (Epinephelus morio) groupers, and Mutton hamlet (Alphestes afer), these predators of parrotfish were uncommon in surrounding waters.…”

Section: Introductionmentioning

confidence: 99%

“…Landings of black grouper remained low until 2002 when gear improvement allowed for greater success in harvesting these large predators (Luckhurst and Trott 2015). At this time, when an apex predator population was being harvested in great numbers by trawling in shallow waters (Luckhurst and Trott 2015), parrotfish were showing increased populations of larger individuals than previous years due to low predator pressure (O'Farrell et al 2015(O'Farrell et al , 2016. Other apex predators that could affect parrotfish population dynamics, Galapagos sharks (Carcharhinus galapagensis, called dusky or puppy sharks in Bermuda) and tiger sharks (Galeocerdo cuvier), faced similar fortunes due to overfishing during the same time period.…”

Section: Introductionmentioning

confidence: 99%

Could marine animal conservation laws be responsible for the decline or extirpation of macroalgal populations in Bermuda over the past century?

Schneider

Flook

2017

Botanica Marina

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Using over 10,000 archival herbarium specimens from Bermuda, we compared the presence or absence of seaweeds from a century ago with our more than 5000 collections from the last 30 years. Populations of parrotfish, important herbivores of macroalgae in the tropics, have increased since the 1993 amendment to the Bermuda 1978 Fisheries (Protected Species) Order. A fish pot ban for Bermuda was put into effect in 1990 to protect a variety of fish including parrotfish and several species of grouper, important predators of parrotfish that were rarely seen in island waters at the time. Intertidal grazing West Indian top shells were reintroduced in 1982 to Bermuda, and since then, along with the rise in parrotfish populations, inshore populations of many macroalgae have dramatically changed. We suggest that several large and abundant Bermuda macroalgal species recorded in the early 20th century appear to have been extirpated or are greatly diminished in sizes of individuals as well as population abundance, and propose that marine animal protections over the past 35 years are a possible reason for the changes we are presently observing.

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Bermuda and the Sargasso Sea

Smith

Warren

2019

World Seas: An Environmental Evaluation

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Parrotfish sex ratios recover rapidly in Bermuda following a fishing ban

Cited by 15 publications

References 21 publications

Leveraging sex change in parrotfish to manage fished populations

Leveraging sex change in parrotfish to manage fished populations

Could marine animal conservation laws be responsible for the decline or extirpation of macroalgal populations in Bermuda over the past century?

Bermuda and the Sargasso Sea

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