Chlorurus bowersi, Bower's parrotfish or the orange-blotch parrotfish, is a species of ray-finned fish, a parrotfish from the family Scaridae. It is found in the Western Pacific Ocean from the Ryukyu Islands of Japan in the north to Java, Papua and the Philippines in the south, [1] and east to Micronesia. This species is found in reef flats and fronts in sheltered areas or where there is moderate exposure to the currents or waves. This is a relatively small parrotfish generally found in pairs which excavates burrows. [2] It feeds on filamentous algae. [3] Chlorurus bowersi was first formally described as Callyodon bowersi in 1909 by the American ichthyologist John Otterbein Snyder (1867-1943) and the type locality was given as Naha, Okinawa, Japan. [4]
Contents
Taxonomy
The Bower’s Parrotfish, Chlorurus bowersi, is a member of the family Labridae [5] and falls under the genus Chlorurus [6] . The genus changed from Scarus to Chlorurus due to a shift in phylogeny using both morphological and molecular characteristics [6] . Within the order Labridae, there are 64 genera that house 452 species [5] . Within the order, cleaning behavior is a fairly universal trait [5] . This is done to remove ectoparasites from other organisms and provides a symbiotic relationship between individuals within the order and other organisms in its ecological niche [5] . It is thought that among the Labridae, a contrasted dark lateral stripe or a dark caudal fin is a present feature or pattern in facultative cleaner species [5] .
Physical Description
Chlorurus bowseri shares many morphological traits associated with the family Chlorurus, including a small, elongated, compressed body and a rounded snout [6] . The dorsal fin of the fish is continuous, accompanied by 9 spines and 10 soft rays [6] . The anal fin of the fish contains 3 spines followed by 9 rays [6] . The pectoral fin of C. bowersi contains between 13 and 17 rays, and the pelvic fin contains 1 spine and 5 rays [6] . The main scales of the fish are cycloid scales and are relatively large, while the fish also has cheek scale rows (1 to 4) as well as median predorsal scales (2 to 8) [6] . The lateral line of the fish consists of 22-24 pored scales and is interrupted [6] . Chlorurus bowersi is a brightly colored blue-green fish with patches of orange on the head, pectoral fins, pelvic fins, and orange streaks throughout the dorsal and anal fins [6] .
The jaw of C. bowersi contains well-developed pharyngeal bones along with a dental plate on each jaw [6] . On the dental plate, there is a beak-like structure to assist with feeding [6] . In comparison to other members of the Labridae family, C. bowersi has a larger weight of its adductor mandible, allowing it to have a greater biting force and powerful jaw mechanics [7] . The interspecific differences in jaw-lever mechanics and the relative weight of the adductor mandible will factor into the grazing ability of the parrotfish [7] . The teeth of C. bowersi are protrusive-shaped rather than flat-shaped, which can be seen in other species [7] .
Within the Labridae family, many species experience protogynous hermaphroditism, resulting in a variety of color patterns throughout growth and sex stages [6] . The growth and sex stages consist of an Initial Phase (IP) and a Terminal Phase (TP) [6] . The IP refers to females and young males and precedes the TP if it occurs [6] . The TP refers to secondary males after undergoing a sex change [6] . Larger males in the Terminal Phase will have brighter colors and are either derived from females through sex changes or are derived from the Initial Phase [8] . Coloration on females and small males is more drab [8] .
Life History Characteristics
Chlorurus bowersi, among the Labridae family, is considered to have an important role in maintaining balance within the coral reef ecosystem [7] . The fish scrapes off algae from the surfaces of dead coral with the assistance of their beak-like dentition, preventing the growth of algae, which allows for the use of the corals by other organisms [6] . This also plays a role in the bioerosion of coral reefs, which is important in the processing of building reef environments [7] . Alongside this behavior, parrotfish are divided into the categories of excavators and scrapers, with Chlorurus being an excavator [9] . Parrotfish feed on the detrital aggregates scraped from the surface of the reef, known as epilithic, or excavate it from the deeper reef substratum, known as endolithic [10] . As they feed directly on plant material, the family is categorized as herbivores [10] .
The spawning and mating tactics of parrotfish vary between species and are known to spawn pelagic eggs with varying times between dawn and dusk [8] . In the Caribbean, spawning can occur in the mornings or afternoons following a high tide, but is most often observed in the afternoon [8] . In the Indo-Pacific, spawning generally occurs after the high tide, which is thought to assist in the facilitation of egg dispersal with the assistance of the ebb tide [8] . C. bowersi has been observed to spawn at high tide [8] . After spawning, C. bowersi has been observed remaining in the area and feeding near the site of spawning [8] . Terminal Phase males are known to be territorial and to pair spawn with females [8] . To combat this, smaller Initial Phase males perform the behavior “streaking,” characterized by a fast intrusion at the time of gamete release between a spawning pair [8] . C. bowersi has been observed primarily participating in pair spawning but has also been observed in group spawning [8] .
Range
Members of the Labridae family can be found in a variety of reef environments, including those of Okinawa [11] , the Indo-Pacific [8] , Taiwan (west-pacific and southern regions) [6] , Penagi [9] , and Indonesia [12] . In Okinawa, no clear trend in the distribution of C. bowersi was observed [11] , but it was seen in the inner reefs (acropora - branching, bottlebrush, dead branching, and dead bottlebrush) and exposed reefs (massive coral, other coral, calcium carbonate substratum). It has been suggested that the distribution of parrotfish is associated with substrate complexity rather than higher coverage of living corals [11] . In Penagi, along the Natuna Island, C. bowersi was found around the shallower areas of reefs alongside other parrotfish species [9] .
Importance to Humans
Chlorurus bowersi holds significance among humans primarily through fisheries [10] , food [6] , economic value [13] , and tourism [10] . Many residents along the coast of Indonesia and within the Coral Triangle rely on the coral reef fisheries and have utilized a variety of fishing methods to do so [12] . This includes various target species, gear, and use of available habitats [10] . While the fisheries are used to support human populations, exploitation of these resources can negatively impact the ecosystem populations as well as the tourism and diving industries [10] .
Parrotfish hold a level of economic significance as many families rely on the fisheries as a source of income [13] and food [12] . In terms of financial income, there are a variety of factors that impact the financial yield, including the situation of the day (month, supply) and the quality of the fish (gear, bruising, size, parasites) [13] . The pricing at local markets can also shift based on consumer income, product availability, supply, demand, days of the week, season, and customer preferences [13] .
Parrotfish are also an important species within the food industry, as many seafood restaurants depend on their presence [6] . Aside from restaurants, the species provides a level of food security within many coastal communities, primarily in developing countries [12] . In Okinawa, especially, parrotfishes are consumed in a variety of ways, including but not limited to sashimi (sliced, raw), maasuni (boiled with salt), and as kamaboko (fried fish meal) [13] .
Status
Bower’s Parrotfish is considered a species of Least Concern [10] . While Chlorurus bowersi does not meet the criteria to be considered a threatened species, it is assessed as a near-threatened species [10] .
This conservation status has been a result of increased fishing pressure, resulting in population declines [10] . The risk of local extinction due to these stressors is rising but is higher in some areas [10] . These overfishing pressures are supported by visible changes in the trophic levels, length, and biomass of the species [12] . One contributing factor to the issue of overfishing comes from the aquarium industry, as this family is included as one of the most collected aquarium species, specifically in Hawaii [10] . Additional stressors of overfishing may be due to the growth in human populations alongside the commercialization of marine resources [12] , increasing the demand for reef fish. Other elements of these stressors include the use of fishing gear and grounds, the size and density of the human population, and the management of them [12] .
The status of other fisheries can also impact on the pressures of overfishing of C. bowersi. As some fishing seasons close, such as Grouper, the fisher's impact on these fish changes [14] . As the ability to fish for a strongly desired fish, such as grouper, is no longer available, fishermen switch their targets to what is available, despite possibly being less desirable [14] . This increase in the number of less desirable fish caught (Chlorurus bowersi) is done to maintain the profit levels of fishermen but adds a significant strain on these populations [14] .
Other threats concerning the conservation status of C. bowersi include the conservation of its habitat, the coral reefs [9] . Stresses on these habitats that impact fish biomass and abundances that include pollution (chemical, sewage, toxic waste, etc), sedimentation, temperature stress, destructive fishing practices, coral bleaching, and invasive species [9] . This impacts the outer small islands of places such as Indonesia alongside the mainland [9] , as these fish support global fisheries.
Conservation Efforts
As a species of Least Concern, the majority of conservation efforts are concentrated on regulations within the fishery of Chlorurus bowersi (3, 7, 8). This comes from the idea that fisheries are shaped by the pressures and use of the fishery itself, which impacts even small geographical areas [12] . Some calls for conservation action may include improved marine reserve networks, fishing regulations, designation and delineation of critical habitat, no-take zones, Marine Protected Areas, monitoring of population statuses, Fish Replenishment Areas (FRAs), and possibly even the establishment of a limited entry program for fisheries such as aquariums [10] . Some strategies may also include restriction of some fishing gears, such as handlines, nets, and traps, to allow for recovery in certain areas and for diversity and sustainability maintenance [12] .
Fishery closures, size limits, and catch quotas also seem to be popular ideas as methods of regulation. These could be most effective if they are done during the reproductive seasons of certain species, as it shifts the pressures from one species to another for a period of time [14] . Although one concern with this effort is the unknown consequences of the shift in fishing upon other species that may experience similar fishing stressors [14] . For fisheries primarily using spearfishing, size regulations are easy to implement as the fisher will know the size of the target before it is caught (9).
| Chlorurus bowersi | |
|---|---|
| | |
| Bower's parrotfish | |
Scientific classification  | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Actinopterygii |
| Order: | Labriformes |
| Family: | Labridae |
| Genus: | Chlorurus |
| Species: | C. bowersi |
| Binomial name | |
| Chlorurus bowersi (Snyder, 1909) | |
| Synonyms [1] | |
| |
