Testing the Cost Effectiveness of Manual
Removal Strategies for the Containment of
Invasive Lionfish Stocks in a Caribbean Reef
Diego Valderrama and KathrynAnn Fields
Food and Resource Economics Department,
University of Florida
North American Association of Fisheries
Economists
8th Biennial Forum, Ketchikan, Alaska
The Lionfish Invasion
• Initially introduced to Florida’s waters in the 1980s, invasive
Indo-Pacific lionfishes Pterois volitans and P. miles have since
then spread throughout the western Atlantic Ocean, Caribbean
Sea, and Gulf of Mexico.
The Ecological Threat
•
Lionfish negatively impact coral reefs through competition with and predation of
native reef species.
− One study done by the University of Oregon found that, within the five-week duration of
their experiment, lionfish caused a 79% decrease in the recruitment of native reef fish
species (Albins 2008).
•
Lionfish have a variety of traits that make them especially resilient in the
Caribbean.
− They have high rates of growth and reproduction as well as cryptic morphology and
venomous spines.
− Lionfish have very few predators: parrotfish and groupers. However, groupers are
targeted by the fishing industry, making them unlikely to serve as an effective form of
biocontrol on lionfish populations.
•
Many of the fish consumed by lionfish are herbivorous.
− A significant reduction in the numbers of herbivorous fish increases the likelihood of a
transition in coral reefs from a coral-dominated to a macroalgae-dominated community.
− https://www.youtube.com/watch?t=16&v=DNdjKqh_h28
The Lionfish Derbies
• A number of countries have created removal programs aimed
at controlling lionfish abundance by spear and net removal of
individual fish; however, little information is available on the
effectiveness of such programs.
How Can One Assess the Effectiveness
of These Derbies?
• Two modeling approaches:
− Age-structured population models: used by fishery biologists to
estimate region-wide mortality targets leading to lionfish
overfishing (Thomas Frazer et al.).
− Ecological models comparing lionfish consumption rates to prey
biomass production rates (Stephanie Green et al.) in order to
compute target densities.
Testing the Ecological Models
• Data were collected on lionfish and prey fish densities during
derbies organized by the UK-based environmental organization
Blue Ventures in the Bacalar Chico Marine Reserve in Belize in
September-October 2014.
− A leading ecological model (Green et al. 2014) was adapted to
estimate target densities for lionfish in the reserve. The same
model was used to estimate consumption rates by lionfish.
− A Holling predation model is currently in the works to describe
the relationship between lionfish densities and CPUE in fishing
derbies.
Bacalar Chico Marine Reserve
Bacalar Chico National Park and Marine Reserve (BCNPMR) is a
protected area and UNESCO World Heritage Site on the
northern part of Ambergris Caye in Belize.
Estimating Target Densities in BCMR
•
Estimating Target Densities in BCMR
•
Estimating Target Densities in BCMR
Estimating Target Densities in BCMR
Estimating Target Densities in BCMR
• Therefore, the coral reef ecosystem in BCMR is able to handle
current lionfish densities. However, an increase in lionfish
numbers will most probably lead to a decline of native fish
stocks.
• These results are consistent with Hackerott (2014), who found
no effect of invasive lionfish stocks on communities of reef fish
in Belize.
• However, lionfish density is low in Belize, what about other
places in the Caribbean and Gulf of Mexico (>200 lionfish/ha)?
Culling of lionfish stocks is imperative.
Bioeconomic Modeling of Fishing Derbies
Holling Predation Model
Ha (Number of lionfish captured per
45-min dive by a two diver team)
• We are in the process of collecting data from fishing derbies to
derive a complete Hollings curve but a preliminary curve has
been derived using data from Frazer et al. (2012) and our data
from Belize.
16
14
12
10
8
6
4
2
-
100
200
300
400
H (Density of lionfish per ha)
500
Preliminary Cost Estimation of a Lionfish Removal Program in
Belize
• Assuming an initial density of 500 lionfish/ha and a target
density of 36 lionfish/ha, a removal program (11 days) would
cost approximately:
•
•
Equipment costs: $1,764.54
Variable costs per ha (boat rental, fuel, crew): $5,500 ($550/day).
•
These removal programs would have to be implemented regularly in
order to keep lionfish numbers in check.
•
Develop markets for lionfish?