Following bonefishes in Hawai‘i: Connecting the dots from ocean to table

Ph.D

Insight into Seasonal Recruitment Dynamics of Juvenile Mulloidichthys vanicolensis and M. Flavolineatus

M.S. University of Hawaii at Manoa 2016.Includes bibliographical references.Goatfish were a culturally important food resource for early Hawaiians and their value is still sustained today as one of the highly sought reef fish in Hawaii’s recreational and commercial fisheries. The most common juvenile goatfishes (oama), Mulloidichthys flavolineatus and M. vanicolensis, exhibit an annual pulse-type recruitment to near shore areas during the summer months in the Main Hawaiian Islands. These annual recruitment events provide food for pelagic and near shore fish as well as food and sport for recreational anglers. Growth rate, habitat preference, hatch date, CPUE, and size and age structure were used to compare recruitment characteristics between species, locations, and years. Oama during 2015 grew faster, were heavier on average, and hatched later than fish during the anomalously high 2014 recruitment. During a typical year, M. vanicolensis recruit earlier than M. flavolineatus and each species is directly linked with a hard or soft substrate type respectively. Limited information exists on these juvenile fishes even though these species have a significant role in the coastal ecology and near shore fisheries. This project aims to shed light on the early life history settlement characteristics of these goatfishes through the study of their annual recruitment patterns

Effects of Gear Restriction on the Abundance of Juvenile Fishes along Sandy Beaches in Hawai'i.

In 2007, due to growing concerns of declines in nearshore fisheries in Hawai'i, a ban on gillnets was implemented in designated areas around the island of O'ahu in the main Hawaiian Islands. Utilizing a 17 year time-series of juvenile fish abundance beginning prior to the implementation of the gillnet ban, we examined the effects of the ban on the abundance of juveniles of soft-bottom associated fish species. Using a Before-After-Control-Impact (BACI) sampling design, we compared the abundance of targeted fishery species in a bay where gillnet fishing was banned (Kailua, O'ahu), and an adjacent bay where fishing is still permitted (Waimānalo, O'ahu). Our results show that when multiple juvenile fish species were combined, abundance declined over time in both locations, but the pattern varied for each of the four species groups examined. Bonefishes were the only species group with a significant BACI effect, with higher abundance in Kailua in the period after the gillnet ban. This study addressed a need for scientific assessment of a fisheries regulation that is rarely possible due to lack of quality data before enactment of such restrictions. Thus, we developed a baseline status of juveniles of an important fishery species, and found effects of a fishery management regulation in Hawai'i

Data from: Effects of gear restriction on the abundance of juvenile fishes along sandy beaches in Hawai'i

In 2007, due to growing concerns of declines in nearshore fisheries in Hawai‘i, a ban on gillnets was implemented in designated areas around the island of O‘ahu in the main Hawaiian Islands. Utilizing a 17 year time-series of juvenile fish abundance beginning prior to the implementation of the gillnet ban, we examined the effects of the ban on the abundance of juveniles of soft-bottom associated fish species. Using a Before-After-Control-Impact (BACI) sampling design, we compared the abundance of targeted fishery species in a bay where gillnet fishing was banned (Kailua, O‘ahu), and an adjacent bay where fishing is still permitted (Waimānalo, O‘ahu). Our results show that when multiple juvenile fish species were combined, abundance declined over time in both locations, but the pattern varied for each of the four species groups examined. Bonefishes were the only species group with a significant BACI effect, with higher abundance in Kailua in the period after the gillnet ban. This study addressed a need for scientific assessment of a fisheries regulation that is rarely possible due to lack of quality data before enactment of such restrictions. Thus, we developed a baseline status of juveniles of an important fishery species, and found effects of a fishery management regulation in Hawai‘i

beach_seine_BACI

beach_seine_BACI.csv is a comma-separated file containing data from beach seine surveys of juvenile fish populations from two sites on windward side of Oahu, Hawai

Map of study area showing gillnet prohibited area (hatched area) in Kailua Bay and open area in Waimanalo Bay (A) on the island of O‘ahu in Hawai‘i (B).

<p>Red circles show sampling locations, and depth contours are colored from light (shallow) to dark (deep).</p

Results of general linear mixed models of catch per unit effort (CPUE) for (A) jacks, (B) bonefishes, (C) flagtails, and (D) Pacific threadfin following a Before-After-Control-Impact (BACI) design to measure differences in juvenile fish populations between a protected area (Kailua) and an unprotected area (Waimānalo), before and after a gillnet closure in Hawai‘i (error bars ± 1 SE).

<p>Results of general linear mixed models of catch per unit effort (CPUE) for (A) jacks, (B) bonefishes, (C) flagtails, and (D) Pacific threadfin following a Before-After-Control-Impact (BACI) design to measure differences in juvenile fish populations between a protected area (Kailua) and an unprotected area (Waimānalo), before and after a gillnet closure in Hawai‘i (error bars ± 1 SE).</p