DISCOVER GUAM
For centuries, fishing has been deeply woven into the cultural fabric of the CHamoru people, representing a cherished way of life. However, there is a mounting concern regarding the declining population of reef fish.
According to officials from Guam's Department of Agriculture's Division of Aquatic and Wildlife Resources, the expansion of commercial fisheries in the past decade has led to a decline in reef fish populations. Moreover, environmental changes such as coral bleaching caused by warmer climates, an increase in crown of thorn starfish consuming coral, soil erosion, and other hazards have further endangered their habitats and impeded population growth.
Leilani Sablan, a CHamoru woman and biology graduate student at the University of Guam, has conducted extensive research for her master's thesis, analyzing over 4,000 local catches. According to her findings, there has been a significant decrease in the population of large fish over the past decade. This decline in both quantity and size of fish has also been observed by elder CHamoru fishermen during interviews, as they compare it to their younger years.
Although it may seem like an easier solution to regulate fishing based on fish taxonomy in order to replenish fish populations, it is not the recommended approach. Brent Tibbatts, a fisheries biologist at DAWR, strongly opposes this idea, particularly in the fragile tropical reef environment. He argued that "We have over 400 species caught in our creel database as fisheries" and that attempting to establish individual regulations for each species is simply impossible.
Research indicates that implementing fishing restrictions for an entire taxonomic group, like parrotfish, is unlikely to yield desired outcomes. Various species within the same family exhibit distinct responses to fishing pressures. Leilani Sablan refers to this phenomenon as compensatory density dependence (CDD). A comprehensive understanding of these dynamics is crucial for ensuring the long-term sustainability of reef fish populations.
When faced with increased fishing pressure, certain species exhibit strong compensatory density dependence. These species not only increase in numbers but also undergo size reduction to counterbalance population losses. The tataga (Naso unicornis) and the Pacific longnose parrotfish (Hipposcarus longiceps) serve as prime examples. Despite facing intense fishing, these species not only manage to survive but also thrive, albeit in smaller sizes.
The removal of larger fish creates room for juveniles and recruits to thrive and develop. However, it's important to note that not all fish within the same family respond in the same manner. A prime example is the Steephead parrotfish (Chlorurus microrhinos), which does not exhibit compensatory density dependence. Instead, it gradually diminishes under the pressures of fishing. This variation highlights the need for a nuanced approach. Not all parrotfish can withstand intense fishing, but we shouldn't generalize and stop catching them altogether. Each species has its limits, and a uniform size limit could lead to imbalanced harvesting. Furthermore, numerous reef fish exhibit sequential hermaphroditism, undergoing gender transitions as they reach maturity. Imposing a size limit would disproportionately impact the genders and hinder the reproductive capacity of the population.
While regulating reef fish is challenging due to compensatory density dependence and variability, responsible fishing remains crucial. We must demand responsible practices to ensure abundant fishing for future generations. Reef fish are not only vital for Guam's needs but also an enduring part of its culture.