© Daniel Cryan 2015

The Galapagos Sailfin Grouper:

A Case Study in the Importance

of Reproductive Biology in

Fisheries Management

Daniel Cryan

Bill Durham

Darwin, Evolution, and Galapagos

10/9/15

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Introduction

The Galapagos Archipelago is world renowned for its unique collection of endemic

coastal and terrestrial life. Here, one can find iconic species such as the Galapagos giant tortoise,

the marine iguana, the flightless cormorant, and of course Darwin’s finches. Many visitors to the

islands are unaware, however, that the waters surrounding the Islands are also home to their own

diverse and fascinating collection of marine life. Here, a confluence of major currents unites

species from the cool southern provinces of Chile and Argentina, with warm-water species from

the west coast of Central America, as well as with tropical species from the Indo-Pacific. These

waters are also home to an impressive number of endemic marine fishes, including the

distinctive Galapagos sailfin grouper, or as it is locally known, the bacalao (Constant, 1992). The

Galapagos sailfin grouper is an apex predator in the rocky reef ecosystems of the Galapagos

Marine Reserve, and has supported a significant fishery in the islands since the early 1920’s. In

recent years, however, fishermen have reported smaller and smaller catches of bacalao, in terms

of both size and overall abundance. In this paper I postulate that the declines in the grouper

population are largely the result of detrimental fishing practices that fail to account for (or even

exploit) the unique reproductive biology of the sailfin grouper. I begin with a discussion of

protogynous hermaphroditism in groupers, its role in reproduction, and the fisheries implications

of targeting large males. I then examine the longevity and slow-maturation of the Galapagos

grouper, and the potential consequence of targeting immature fish. Lastly, I discuss the role of

spawning aggregations in grouper reproduction, and the importance of protecting key spawning

sites from fisheries exploitation. Finally, I make a series of recommendations, based on my three

hypotheses, on what conservation measures should be implemented to ensure the future of the

Galapagos sailfin grouper.

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Biological and Socioeconomic Background

The bacalao or Mycteroperca olfax is a member of the subfamily Epinephelinae, a

diverse group of fishes found worldwide, known colloquially as “groupers.” Taxonomists have

recently reevaluated the phylogenetic lineage of this group of fishes, placing groupers alongside

soapfishes and fairy basslets in the larger family Epinephelidae, separating them from the closely

related anthias and sea basses, which now form their own family Serranidae. There are 16 genera

and 163 species of groupers found worldwide, with 10 species and 6 genera found in the

Galapagos Marine Reserve (Craig, 2007). Of these 10, the bacalao is the largest and most

ecologically important grouper found in the Islands, growing to over 120 cm (4 ft.) long. Like

most groupers, the Galapagos grouper has a large robust body with a wide truncate caudal fin. Its

head and mouth are both large, and it is a fairly slow, deliberate swimmer. The sailfin grouper

gets its name from its distinct dorsal fin, in which the second and third spines are elongated,

giving it a signature sail-like curve. Most individuals are grayish brown to olive green in color,

and often have light spotting and vertical markings along their sides, (though a small portion of

the population, known locally as the bacalao rey or “king grouper,” are a bright yellowish gold

color over their entire bodies) (Deloach, 2003).

In most places, groupers are among the top predators in their ecosystem, and the

Galapagos is no exception. Like its relatives worldwide, the Galapagos grouper feeds on a

variety of crustaceans and small reef fish, and is only susceptible (as an adult) to species such as

sharks or larger groupers. One study found that sailfin grouper fed mainly on the pacific

creolefish (Paranthius coronus), another smaller grouper found throughout the islands. Like

other large groupers, the bacalao is an ambush predator, spending most of its time cruising near

the bottom, hiding near the mouths of caves and under ledges, waiting to strike out at

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unsuspecting fish. Juveniles are often found in shallow mangrove forests and sandy lagoons,

while adults tend to live in deeper waters around rocky reefs, drop offs, underwater lava ridges,

and other vertical structures (Grove, 1997). Unlike many other groupers worldwide, who have

grown wary of humans due to overfishing, the Galapagos grouper is still fairly gregarious (a trait

common in species throughout the islands) and will sometimes approach divers or snorkelers

with curiosity (Craig, 2011).

An adult Galapagos grouper comes out from an underwater cave. © Daniel Cryan 2015

In the 1920’s, the first commercial fishery for Galapagos grouper began in the

Archipelago. It was established by a group of Norwegian settlers who caught, dried, and salted

the fish, so that they could be exported to mainland Ecuador. Many fish were used as the main

ingredient in the traditional Ecuadorian dish Fanesca, a popular Easter stew. (Although this fact

may seem trivial or irrelevant now, it will prove important later on when discussing the decline

of the bacalao). This fishery not only marked the beginning of the exploitation of bacalao, it also

heralded the beginning of the finfish fishery as a whole in the Galapagos (Lacquet, 2007). Over

the next several years, more and more fishermen traveled to the relatively untouched waters of

the islands to tap into the seemingly endless supply of fish. This growth coincided with the

globalization of the Islands as a whole. Over the second half of the 20th Century, the number of

tourists and residents in the islands increased exponentially, placing heightened pressures on the

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Islands’ marine life. During the 1990’s, at the peak of the sea cucumber fishery, there was a

record high of nearly 1200 registered Galapagos fishermen (Castrejón, 2013).

Though bacalao is best known for its use in Fanesca, it is also delicious baked with a side of limes. © Daniel Cryan 2015

During this period of unprecedented growth, however, fishermen and researchers began

to notice a change in the composition and size of the fishermen’s catch. In a reconstruction of the

total catch from 1950 to 2010, Schiller et al. found that the composition of the catch had changed

significantly over time. Serranids (the family containing the bacalao, as well as other groupers

and sea basses) had once comprised more than two thirds of the total catch, but now they only

accounted for about a quarter of the total, and had been replaced by species such as tunas and

mullets (Schiller, 2013). Another study from Burbano et al. looked at the reported “best day’s

catch” of Galapagos grouper amongst different age groups of fishermen. They found that older

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fishermen used to catch significantly more Galapagos grouper than the younger generations, and

that the fish caught a few decades ago were also larger (Burbano, 2014). These studies, along

with the general absence of bacalao in fishermen’s catches nowadays, indicate that this species

has experienced some level of decline over the past few decades. Determining the precise cause

of this decline will be crucial for reversing this trend and ensuring the long term viability of this

species.

Reconstructed Galapagos fish catch from 1950 to 2010. © Schiller 2013.

My Hypotheses

When postulating reasons for the decline of a given species of food fish, it’s often

dangerous to oversimplify the situation and assume that fishermen are simply catching too many

fish. This fails to account for the nuances of the situation, and will inevitably lead to ineffective

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or impractical conservation measures. A more practical approach is to examine the life history of

a given species, and evaluate how fishing effort may influence a species’ ability to survive and

reproduce. In the case of the Galapagos grouper, I propose that the majority of the decline over

the past few decades can be directly attributed to fishing practices that work against the

grouper’s unique reproductive biology. Specifically, fisherman have traditionally harvested large

males, creating a skewed sex ratio. Nowadays, they target juveniles, before they have the ability

to reproduce. And lastly, they often target grouper spawning aggregations, which once again

threatens the population’s long-term viability.

It is common practice for fishermen to target the largest fish possible. Larger fish equate

to higher profits at market, and so it is in the best interest of a fishermen to catch the largest fish

possible. As a result, in places where overfishing occurs, it is usually the largest fish that are the

first to go, as long term survival becomes increasingly difficult. The Galapagos grouper is no

exception to this rule. Fishermen are now catching increasingly smaller fish, as large individuals

become extremely rare (Burbano, 2014). For many species this is just an unfortunate result of

overfishing, and not a problem in and of itself, but for the Galapagos grouper, this lack of large

individuals is especially problematic. This is because the bacalao, like many other groupers, is a

protogynous hermaphrodite. A protogynous hermaphrodite is an organism that begins its life as a

female, but later in life transitions to male, once it has reached a certain size (Bhandari, 2006).

The evolutionary advantage of such an adaptation is that large healthy males are favored by

natural selection and that there is a low likelihood of closely related species interbreeding,

because at any given life stage they are all the same gender (Ghiselin, 1969).

In 1993, Coello and Grimm conducted a study of the life history of Galapagos grouper,

by examining the age, size, and sex of fish caught by Galapagos fishermen. They found a highly

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skewed sex ratio of 48 females for every 1 male in the local population. Due to the nature of

protogynous hermaphroditism, it’s not uncommon to see skewed sex ratios in the wild, even

amongst healthy populations. Yet this ratio was still higher than those seen in any other related

species of groupers (Coello, 1993). And in 2015, a study by Usseglio et al. found that the ratio

was now even higher, reaching 67 females for every 1 male. The same study found that it took

over 15 years for half of all groupers to become male, and that the average size of sex change

was 83.7 cm. With so few large males in the population, it becomes increasingly difficult for the

sailfin grouper to spawn successfully. This is problematic because without reproduction the

population cannot replenish itself, and will continue to dwindle until no fish remain. Protecting

large males will be essential in the conservation of the Galapagos grouper (Usseglio, 2015).

Sex Distribution of Galapagos Grouper. © Usseglio et al. 2015

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Ironically, the historic targeting of large males leads directly to the next major problem

facing the Galapagos grouper, which is the targeting of immature juveniles. When fishermen no

longer have large fish to catch (because these fish are very rare) their only option is to either

target other species (which can be seen in the expansion of the Galapagos fishery towards

species like tuna and mullets) or to target smaller individuals (Schiller, 2013). This can prove

problematic if fishermen begin to target immature juveniles, who are not yet able to reproduce.

And unfortunately for the bacalao, thanks to their unique reproductive biology, this is exactly

what has begun to occur.

Size Distribution of Galapagos Grouper. © Usseglio et al. 2015

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In their 2015 study, Usseglio et al. examined grouper growth rates and age of maturation

by correlating total body length, gonad development, and otolith ring formation. An otolith,

commonly known as a “fish ear bone,” is a calcium carbonate structure located in the heads of

bony fish. Every year another ring of carbonate is deposited, providing an accurate metric for a

wild fish’s age. The researchers found that, like many other large groupers, the bacalao grew

relatively slowly and had a high longevity. In addition, they found that the average age of

maturation for the groupers was 7.8 years old, with an average size of 61.1 cm. This meant that,

of all the fish caught by the fishermen, 73% were juveniles, and only 27% were mature. This

high abundance of juveniles is an especially alarming result, considering these individuals are

not yet able to reproduce and propagate the species. Ensuring that juvenile sailfin grouper are

able to mature and reproduce, before they are subject to fisheries pressure, should be a top

priority for conservation of this species (Usseglio, 2015).

Finally, as if the situation weren’t hard enough for the Galapagos grouper, evidence

suggests that fishermen are targeting them in the very act of reproduction. And once again, it is

the sailfin grouper’s unique reproductive biology that makes it so vulnerable. Large groupers

typically reproduce in what are known as “spawning aggregations.” During one of these

aggregations, several mature fish meet up at select locations in groups that can range from 20-30

to tens of thousands, depending on the species. Researchers believe that changes in the lunar

cycle trigger these migrations to the spawning locations, as spawning always occurs on roughly

the same day in the lunar cycle each year. During the late afternoon and early evening, the

mature fish will all swim together and release their gametes in one spectacular mass-fertilization.

(Sala, 2001). It was unknown for many years whether or not the bacalao engages in spawning

aggregations, simply because little research had been done on the species, however, in 2015

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Salinas-de-León et al. observed the first sailfin grouper spawning aggregations off Darwin and

Wolf Islands, confirming that this behavior does in fact exist in this species (Salinas‐de‐León,

2015).

This is worrying, considering that elsewhere in the world fishermen often target

spawning aggregations, due to the relatively high abundance of fish found there. And because

they target fish in the very act of reproduction, many large adults are removed from the

population, preventing any future breeding, and endangering the future of the species as a whole.

In the Caribbean, the Nassau grouper (Epinephalus striatus) has suffered severe regional

declines, which are largely the result of fishermen targeting their spawning aggregations. But are

fishermen in the Galapagos doing the same? The circumstantial evidence certainly seems to

suggest so. The sailfin grouper spawning season occurs from October to March, during a period

of high marine productivity in the Galapagos. The fishing season for this species also historically

occurred during the same period, though nowadays they are fished year round in an attempt to

compensate for the decline. And this period also occurs right before the Christian religious

holiday of Easter, during which Fanesca, the traditional dish made from bacalao, is served

throughout all of Ecuador. What this suggests, is that fishermen have historically targeted

bacalao during this period due to their high spawning abundance which conveniently occurred

right before Easter. Additionally, all four spawning sites discovered by Salinas-de-León et al. are

within the legal fishing areas of the Galapagos Marine Reserve, so any fishermen who wanted to

target these aggregations would be completely within their legal rights to do so. Consequently,

protecting these important spawning sites is crucial for ensuring the survival of this species

(Salinas‐de‐León, 2015).

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Conservation Recommendations

Though the situation for the Galapagos grouper may seem dismal (having three major

threats to its reproductive viability), the bright side is that identifying these threats allows

researchers and policymakers to make specific and concrete recommendations for the protection

of this species. Currently, there are no specific regulations in the Galapagos governing the

fishery of the bacalao. If we are to protect this species, this must change immediately. The first

step is to introduce a temporary maximum size limit of 83.7 cm (the average age of maturation

for males). This will ensure that large males are protected, at least until the population has begun

to rebound, at which time the maximum limit could be readjusted or removed. The next step

would be to implement a minimum size limit of 61.1 cm, to protect juvenile fish that have not yet

matured and reproduced. Minimum size limits are standard practice in fisheries management,

and so this limit should remain relatively permanent, with room for adjustment, as is necessary.

In order to protect grouper in the actual act of spawning, all identified spawning areas should be

set aside as no-take zones, and researchers should continue to search for new spawning areas,

which should also be protected (Castrejón, 2013). Also, a fishing closure during peak spawning

months (October to March) should also be implemented, at least until the population has begun

to rebound. Another novel idea to help the grouper population would be to set up a grouper

hatchery and aquaculture center in the islands, to help supplement the wild population while it is

recovering. Such a venture would also provide employment to local fishermen, and help alleviate

the economic losses caused by the new fisheries regulations.

Conclusion

The Galapagos sailfin grouper is truly a remarkable species. It is a top predator in the

local marine ecosystem, a unique endemic species of the Galapagos Archipelago, a popular sight

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amongst divers and snorkelers, and perhaps most importantly, a culturally and economically

important fish for the islands. This fish holds the unique distinction of supporting the very first

fishery in the Galapagos, one that would eventually grow and expand into other fisheries that

would change and define the identity of these Islands. In this sense, the Galapagos grouper is

important to these Islands, not only practically in terms of its ecosystem importance, but

symbolically to the Islands as a whole. And although this species is facing a multifaceted

decline, the situation is not hopeless. Now that we have identified the major threats facing this

species (fishermen targeting males, targeting juveniles, and targeting spawning aggregations) we

can take the steps necessary to protect the grouper. And in general, it is worth remembering, that

conservation is not just for the species being conserved, it’s for us too. This is especially true for

fish, because if the fish disappears, so does the fishery, and thus the fishermen’s livelihood. So as

we move forward let us remember that it is not only the bacalao’s future that is at stake, but ours

as a well.

A Galapagos grouper adorns this mural outside the Puerto Ayora Fish Market. © Daniel Cryan 2015

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“It is not only the bacalao’s future at stake, but ours as well.” © Daniel Cryan

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