Parrotfish: An overview of ecology, nutrition, and reproduction behaviour

2.1 Biologic study

Farasan Islands (16°43′44.16′′N, 42°4′24.47′′E) in the southern Red Sea's Longnose Parrotfish (Hipposcarus harid) gather in big schools once a year in the spring (Gladstone 1996). The annual Hareed Festival in Saudi Arabia is conducted in honor of this meeting, which has been well-known to the country's people for the past two centuries.Some 200–500 individuals (20–30 cm total length) were estimated to be crammed into 3–4 m diameter schools. Each school contained only a single fish in the terminal phase, the only exception being a single pale-colored fish in the early stage. There were no groups of parrotfish seen outside of the lagoon. As part of preparations for this year's Hareed Festival, local fishermen capture 3,000–5,000 parrotfish in the lagoon on the fifth day of the aggregation, when most schools have arrived. People from around the region then converge on the beach per custom. They wait for a signal and then rush into the lagoon, armed with nets. The prince of the Farasan region awards a prize to the fisherman who catches the most biomass, in keeping with a long-standing tradition. It is forbidden to sell the catch at the festival. Thus, any fish that appear to be unripe (no running eggs or milt observed) are given away as gifts, eaten by the winners, or thrown away. There are no more live fish in the tank after about 60 min. Despite this heavy harvesting, the annual gathering still occurs. The above-described parrotfish aggregation can only be found in the Red Sea off the Farasan Islands. It is unknown why or how this particular species gathers in this lagoon at the same time each year, but it does. Parrotfish aggregations have never been observed in this way before, and it doesn't appear to be a spawning aggregation. It was recently established that the yearly coral spawning event occurs one day after the aggregation always begins on the day after the full moon (Bouwmeester et al. 2012). A long-running harvest festival and cultural event are based on this annual aggregation, no matter the reason. The Farasan Islands (16°43′44.16′′N, 42°4′24.47′′E) in the southern Red Sea's Longnose Parrotfish (Hipposcarus harid) gather in big schools once a year in the spring (Gladstone 1996). The annual Hareed Festival in Saudi Arabia is celebrated in honour of this gathering, which has been well-known to the citizens of the kingdom for the last two centuries. Some 200–500 individuals (20–30 cm total length) were estimated to be crammed into 3–4 m diameter schools. Each school contained only a single fish in the terminal phase, the only exception being a single pale-colored fish in the early stage. There were no groups of parrotfish seen outside of the lagoon. As part of preparations for this year's Hareed Festival, local fishermen capture 3,000–5,000 parrotfish in the lagoon on the fifth day of the aggregation, when most schools have arrived. People from around the region then converge on the beach per custom. They wait for a signal and then rush into the lagoon, armed with nets. The prince of the Farasan region awards a prize to the fisherman who catches the most biomass, in keeping with a long-standing tradition. It is forbidden to sell the catch at the festival. Thus, any fish that appear to be unripe (no running eggs or milt observed) are given away as gifts, eaten by the winners, or thrown away. There are no more live fish in the tank after about 60 min. Despite this heavy harvesting, the annual gathering still occurs. The above-described parrotfish aggregation can only be found in the Red Sea off the Farasan Islands. It is not known why or how this particular species gathers in this lagoon simultaneously each year, but it does. Parrotfish aggregations have never been observed in this way before, and it doesn't appear to be a spawning aggregation. It was recently established that the yearly coral spawning event occurs one day after the aggregation always begins on the day after the full moon (Bouwmeester et al. 2012). A long-running harvest festival and cultural event are based on this annual aggregation, no matter the reason.

2.2 Environmental study

In the Arabian region, 20 parrotfish species have been discovered, with the majority (17 species) found in or near the Red Sea. Many of these species are indigenous to their location. Scarus arabicus and Scarus zufar are restricted to the Arabian Sea and Oman's southern shore, whereas Scarus persicus is limited to the Arabian Gulf and Oman's coast (Choat et al. 2012). As a result, the taxonomic mix of parrotfishes in the Arabian Gulf, Arabian Sea, and Red Sea is very subregional (Hoey et al. 2016b). The Arabian Gulf has two species (Sc. persicus and Scarus ghobban), the Arabian Sea has two species (Sc. persicus and Scarus ghobban), and the Red Sea has a variety of scraping and excavating species (Hoey et al. 2016b). Despite the similarity in abundance and biomass of parrotfishes between habitats in the Red Sea (Khalil et al. 2017), the absence of reef development and clearly defined reef zones hinder inter-habitat comparisons in the Arabian Sea or Arabian Gulf. From the Red Sea to the Arabian Sea and Arabian Gulf, the species richness and abundance of excavating parrotfishes decrease. Given the region's biogeography, the decline in species richness is to be anticipated, but the lack of digging parrotfishes in the Arabian Sea is notable.Despite the rarity of excavating parrotfishes, Oman's coast has two kinds of excavating parrotfishes. The lack of excavating parrotfishes on Arabian Sea reefs contrasts with the abundance of scraping parrotfishes, implying that their feeding or nutritional ecology may contribute to these disparities. Scratching and digging parrotfishes eat on identical surfaces (dead coral or carbonates covered in EAM), but their bite depth varies. Excavating parrotfishes takes deeper bites and removes more of the underlying substrate with each bite than scraping parrotfishes (Hoey and Bellwood 2008). In this area, the stony reef and the difference in feeding 0habits may have contributed 282 Parrotfish Biology Scraper 30°N 20°N 10°N B. Diggers SAUDI ARA Yemen m Omani SAUDI ARA UAE Oman Yemen 0 250 500 k. Absentee parrotfishes excavating Hard surface feeding has been linked to dental damage in giant Atlantic parrotfishes (Bonaldo et al. 2007). Only two species (Sc. persicus and Sc. ghobban) have been recorded during comprehensive surveys of reefs in the southern Arabian Gulf, with densities of fewer than one individual per 1000 m² (Feary et al. 2010). These reefs have low numbers of other herbivorous fishes (i.e., Siganidae, Acanthuridae) (Feary et al. 2010, Burt et al. 2011). Although parrotfish populations have declined globally due to fishing (Taylor et al. 2014), they are not a priority target in the Arabian Gulf (Grandcourt 2012). Temperature shifts can affect tropical species, especially reef fishes, which have evolved in relatively stable thermal conditions and have a lower thermal tolerance than temperate species (Tewksbury et al. 2008). The Arabian Gulf's significant temperature variance (annual temperature range 20 °C) may prevent many tropical species from settling here. The biodiversity of the Arabian Gulf's reef fish is endangered (Burt et al. 2011). Importantly, due to the restriction of feeding during the cooler months, rates of grazing and erosion inside the Arabian Gulf and to a lesser degree, the Arabian Sea may be much lower than these estimates. According to preliminary data for Sc.persicus from the northern Arabian Sea, a 6 °C reduction in water temperature (from 29 °C to 23 °C) resulted in a 50–60% decrease in bite rate (Hoey unpublished data). While variations in the nutritional content of food cannot be ruled out, the feeding decrease is consistent with projected temperature-induced changes in metabolic needs.

2.3 Seasonal search for food

In their natural habitat, parrotfishes must choose from various food sources whose availability and nutritional makeup are subject to spatial and temporal variation. Parrotfish strive to meet their daily nutrient requirements to maintain a balanced diet (Rubio et al. 2003). In this case, parrotfish are more likely to seek out food items that contain nutrient deficiencies in the environment and are required in more significant quantities to fulfill life functions (Pretorius et al. 2012). It is exciting to see if coral reef grazers, particularly parrotfishes, respond similarly to their terrestrial counterparts or if they have evolved different mechanisms. Evidence suggests that parrotfishes can choose nutritionally richer resources (Fong et al. 2006).

It is exciting to see if coral reef grazers, particularly parrotfishes, respond similarly to their terrestrial counterparts or if they have evolved different mechanisms. Evidence suggests that parrotfishes can choose nutritionally richer resources (Furman and Heck 2008). There is comparatively more information on the seasonal variations in feeding rate in parrotfishes. Those studies examining parrotfish eating rates over various seasons frequently report (Hatcher 1982) that Summertime feeding rates are higher. Nutritional quality (Burkepile and Hay 2009) and productivity (Russ 2003) correlate positively with parrotfish feeding rate. These variables are more significance in the summer, and the observed increases in feeding rates may be due to Their combined effects with higher temperatures (see below). Other factors that could cause Seasonal variations that influence parrotfish feeding rates include inhibitory peptide concentrations, Ash content, and secondary metabolites (Steinberg 1989, Amade and Lemée 1998). Extreme summer temperatures in the southern Red Sea may prevent parrotfish and other grazing fishes from foraging on shallow reef flats (Afeworki et al. 2013). Amade and Lemée (1998) found olites and ash content significant. As a result, turf biomass in these shallow zones reaches an annual maximum (Ateweberhan et al. 2006). Increased irradiance and temperature in deeper reef zones may facilitate higher productivity, prompting reef grazers and parrotfishes to forage more in deeper zones during summer than in other seasons (Afeworki et al. 2013). Parrotfishes' growth has been studied using age-length data, which reads age (annuli) from sections of hard parts, primarily otoliths (Choat and Robertson 2002). Since the 1970s, researchers have discovered that otoliths from tropical fish form annual alternating growth bands (Fowler 2009). This species' body condition and liver lipid content rise during the spring and peak in the early summer (Afeworki 2014). Van Rooij et al. (1995) studied variation in body condition and growth in Sp. viride in Bonaire, the Caribbean, discovered all social categories of Sp. viride achieved better body condition, and all individuals (except the largest territory holding males) showed peak growth during the summer. This coincides with the Caribbean's peak season for EAM productivity (Adey and Steneck 1985, Carpenter 1986, Ferrari et al. 2012).

2.4 Tracking using new technology

During June and July, the habitat use of juvenile southern flounders (Lichthys lethostigma) was studied using acoustic telemetry in a shallow estuarine seascape 2011. Fine-scale movement and habitat use of P. lethostigma was investigated with an acoustic positioning system placed in a seascape that varied in habitat type, physicochemical conditions, and bathymetry. Different habitat types were examined with Euclidean distance-based analyses. Further, generalized additive models were used to determine the relative importance of habitat type relative to physicochemical conditions and bathymetry. Tracks of P.lethostigma ranged in the distance between 1477 and 8582 m, and speed was 4·2 ± 1·1m min − 1 (mean ± s.e.) for all P. lethostigma combined. Depth, slope, and habitat type had the most influence on P. lethostigma occurrence, and deep sandy areas with shallow slopes were used most frequently. In addition, depth use by P.lethostigma was influenced by tidal cycles, indicating habitat use varies temporally and is dynamic. Finally, temperatures < 30.5 °C were used more than warmer waters within the study area. The results successfully identify movements by juvenile P.lethostigma, and indicate that definitions of essential habitats need to account for dynamics in habitat use. (Furey et al., 2013). Also, some elasmobranchs are thought to use shallow temperate estuaries during warmer months because these habitats may provide thermal physiological advantages. However, extensive loss and degradation of southern California bays and estuaries have reduced coastal species' access to estuarine habitats. While restoration of southern California estuaries has increased over the last two decades, little is known about the recovery of ecological function. Top predators are considered important indicators of ecological function restoration in many ecosystems, including estuarine habitats. In this study, abundance surveys and acoustic telemetry were employed to examine how gray smooth-hound sharks (GSH) use the newly restored Full Tidal Basin (FTB) of Bolsa Chica. GSH was most abundant inside the FTB during the spring and summer, and numbers decreased during the winter. Over 83% of all individuals (n = 336) caught were immature juveniles and were most abundant when water temperatures were between 20 and 22 °C. Sharks fitted with acoustic transmitters (n = 22) were continuously detected for 6–153 days (August 2008–December 2009). Forays into coastal waters were uncommon until individuals left for the season. GSH selected warmer habitats within the middle FTB butalso exhibited diel movements along the basin. GSH was most often founciated with mud and eelgrass at night, presumably for feeding. Since its restoration, population and behavioral data suggest that the FTB may provide juvenile GSH with a suitable seasonal environment for feeding and growth. Acoustic telemetry is now a key research tool used to quantify juvenile salmon survival, but transmitter size has limited past studies to larger smolts (>130 mm fork length). New, smaller, higher-frequency transmitters (“tags”) allow studies on a larger fraction of the smolt size spectrum (>95 mm); however, detection range and study duration are also reduced, introducing new challenges. The potential cost implications are not trivial. With these new transmitters in mind, we designed, deployed, and tested the performance of a dual-frequency receiver array design in the Discovery Islands region of British Columbia, Canada. We double-tagged 50 juvenile steelheads (Oncorhynchus mykiss) with large 69-kHz tags (VEMCO model V9-1H) and small 180-kHz tags (model V4-1H). The more powerful 69-kHz tags were used to determine the fish presence to estimate the detection efficiency (DE) of the 180-kHz tags. We then compared the standard error of the survival estimate produced from the tracking data using the two tag types, which has important implications for array performance and hypothesis testing in the sea. Perfect detection of the 69-kHz tags allowed us to determine the DE of the 180-kHz tags. Although the 180-kHz tags began to expire during the study, the estimated DE was acceptable at 76% (SE = 9%) when we included single detections. However, 95% confidence intervals on steelhead survival (64%) were 1.5 × larger for the 180-kHz tags (47–85% vs. 51–77% for 69 kHz) because of the reduced DE (Rechisky et al., 2020). Moreover, research on fish movement and habitat use in large tropical rivers is urgently needed to protect fisheries that are a primary source of protein for millions of people. In this pilot study, acoustic telemetry was used to monitor the movements of wild catfishes in a 94.6rkm reach of the Mekong River, which functions as the border between Thailand and Lao People’s Democratic Republic (PDR). Twenty fish were tagged, released in May 2006 and monitored through May 2007 with 17 fixed-site acoustic receivers. Ten receivers had detection probabilities ranging from 0.67 to 1.00, and five had detection probabilities of 0.50 or less. Detection probability was not correlated with river width. Eighteen (90%) of the tagged fishes were detected by at least one receiver. Monitoring durations of individual fish ranged from 0.1 to 354.4 days. The longest total movement was 88.3rkm, while the longest upstream movement was 52.1rkm. Movement rates ranged from 0.1 to 156.7 rkm/d. This work provided preliminary data on the movement patterns of wild Mekong catfishes. The methods and lessons learned from this study can be used for future positional telemetry research to address management-relevant uncertainties about migration corridors, habitat use, the efficacy of fish reserves, and river development planning (Naughton et al., 2021).

2.5 Seasonal stampede migratory of parrotfish to Farasan Island

Farasan Island is located in the southern parts of the Red Sea, approximately 40 km from Jazan, Saudi Arabia. Geographically, the area is bounded between 16°8″ to 17°10″ N and 41°22″ to 42° 0″ E (Fig. 1). April to October is the summer season, and November to March is the low-hot season on Farasan Island. The annual average temperature of Farasan Island is 30 °C. The relative humidity is 70 to 80% in winter and 65 to 75% in summer. The month with the greatest rain in the area is April. The research region is recognized by its unusual geography in southern Saudi Arabia, where coral reefs multiply annually around these islands.The water is considered warm due to the shallowness of the seawater around the islands. For these reasons, large swarms of migratory haread fisheries flock to the shores of these islands to overtake and relax for a few days from the end of March and the beginning of April of each year. Through the questionnaires distributed to several fishermen in the ports of these islands, it was found that these fish did not carry eggs during this period and that there were no new flocks with them. Referring to these questionnaires, two types of Hipposcarus haread fisheries have been observed. The first is seasonal stampede migratory fish (Fig. 2), and the second is endemic fish, which can be found in the fishermen's nets for every daily fishing trip (Fig. 3). During the arrival of these migratory fish, the Municipality of Farasan Islands organizes the Haread Festival in the presence of the Prince of Jazan Province (Fig. 4).

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Fig. 2

Seasonal Stampede Migratory haread.

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Fig. 3

Endemic Hipposcarus haread.

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Fig. 4

Festival migratory Hipposcarus haread in the Farasan Islands.

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