[et_pb_section fb_built=”1″ _builder_version=”3.22.3″ background_image=”https://moevarua.com/wp-content/uploads/2019/04/fondo.jpg” custom_padding=”30px|0|0|0px|false|false”][et_pb_row _builder_version=”3.22.3″][et_pb_column type=”4_4″ _builder_version=”3.19.18″][et_pb_text _builder_version=”3.19.18″ header_font=”||||||||” header_font_size=”40px” header_line_height=”1.3em”]
Plastics in Yellow Tunas and their prey along the coast of Rapa Nui
[/et_pb_text][/et_pb_column][/et_pb_row][et_pb_row custom_padding=”0|0px|27px|0px|false|false” _builder_version=”3.22.3″][et_pb_column type=”4_4″ _builder_version=”3.19.18″][et_pb_image src=”https://moevarua.com/wp-content/uploads/2019/04/Atun.png” _builder_version=”3.19.18″ max_width=”80%” module_alignment=”center”][/et_pb_image][et_pb_text _builder_version=”3.19.18″]
© Photo by Nicolás Ory
[/et_pb_text][/et_pb_column][/et_pb_row][et_pb_row custom_padding=”0|0px|0|0px|false|false” module_class=” et_pb_row_fullwidth” _builder_version=”3.22.3″ width=”89%” width_tablet=”80%” width_last_edited=”on|desktop” max_width=”89%” max_width_tablet=”80%” max_width_last_edited=”on|desktop” make_fullwidth=”on”][et_pb_column type=”4_4″ _builder_version=”3.19.18″][et_pb_text _builder_version=”3.19.18″ text_font=”||||||||” text_font_size=”15px” text_line_height=”1.8em”]
Tunas are one of the most emblematic fish of Rapa Nui: they have provided food to the Rapanui people for centuries, and are now a delicacy that tourists from all around the world can enjoy when visiting the island. These large predatory fish, the heaviest of which can weight several hundreds of kilograms are mostly fished by angling barehanded, a traditional fishing technique that has been used for centuries in Rapa Nui. This art of fishing is physically challenging and requires a perfect knowledge of the fish’s ecology and feeding behaviour; this is why artisanal fishing has been sustainable for centuries in Rapa Nui. However, the intensive fishing of tunas by large fishing vessels in the open ocean is currently jeopardizing the sustainability of the population of tunas in the south Pacific and, in turn, the ecological and economic health of Rapa Nui.
[/et_pb_text][et_pb_image src=”https://moevarua.com/wp-content/uploads/2019/04/mesoplastico.png” align=”center” _builder_version=”3.19.18″ max_width=”35%”][/et_pb_image][/et_pb_column][/et_pb_row][et_pb_row custom_padding=”93px|0px|60px|0px|false|false” _builder_version=”3.22.3″][et_pb_column type=”4_4″ _builder_version=”3.19.18″][et_pb_text _builder_version=”3.19.18″]
© Photo by
Jaime Aburto
[/et_pb_text][/et_pb_column][/et_pb_row][/et_pb_section][et_pb_section fb_built=”1″ _builder_version=”3.22.3″ custom_padding=”54px|0px|0|0px|false|false”][et_pb_row custom_padding=”0|0px|27px|0px|false|false” _builder_version=”3.22.3″][et_pb_column type=”2_5″ _builder_version=”3.19.18″][et_pb_code _builder_version=”3.22.7″][bsa_pro_ad_space id=3][/et_pb_code][/et_pb_column][et_pb_column type=”3_5″ _builder_version=”3.19.18″][et_pb_text _builder_version=”3.19.18″ text_font=”||||||||” text_font_size=”15px” text_line_height=”1.8em” header_font=”||||||||”]
The presence of plastic litter abundant in the waters around the coast of Rapa Nui is another threat for the fragile ecosystem of the island. Plastics do not originate locally: large items, such as buoys, cooler boxes and ropes, are discarded by large factory ships cruising offshore the island. Other plastic items of common use come from the surrounding continents. Indeed, once at sea, floating plastic items can be transported over large distances by winds and currents within oceanic gyres at the centre of which they accumulate in very large quantities. During the time plastics float at sea, they fragment into smaller pieces under the combined effects of sunlight, temperature, chemical degradation and mechanical abrasion. In the centre of the South Pacific Gyre, close to Rapa Nui, small broken plastic fragments of various sizes, from several centimetres (meso-plastics) to millimetres (micro-plastics), are very abundant and commonly ingested by many marine organisms.
[/et_pb_text][/et_pb_column][/et_pb_row][et_pb_row custom_padding=”0|0px|27px|0px|false|false” _builder_version=”3.22.3″][et_pb_column type=”4_4″ _builder_version=”3.19.18″][et_pb_text _builder_version=”3.19.18″ text_font=”||||||||” text_text_color=”#ffffff” text_font_size=”18px” header_font=”||||||||” background_color=”#000000″ custom_margin=”||” custom_padding=”8px||8px”]
Microplastics are transfered to the predator
fromtheir prey, but rae readily egested.
[/et_pb_text][et_pb_image src=”https://moevarua.com/wp-content/uploads/2019/04/Dibujo-Microplástico.jpg” _builder_version=”3.19.18″][/et_pb_image][/et_pb_column][/et_pb_row][et_pb_row custom_padding=”0|0px|27px|0px|false|false” _builder_version=”3.22.3″][et_pb_column type=”4_4″ _builder_version=”3.19.18″][et_pb_text _builder_version=”3.19.18″ text_font=”||||||||” text_text_color=”#ffffff” text_font_size=”18px” header_font=”||||||||” background_color=”#000000″ custom_margin=”||” custom_padding=”8px||8px”]
Tunas directly capture mesoplastics,
wich acumulate in the fish’s gut..
[/et_pb_text][et_pb_image src=”https://moevarua.com/wp-content/uploads/2019/04/Dibujo-Mesoplático.jpg” _builder_version=”3.19.18″][/et_pb_image][/et_pb_column][/et_pb_row][et_pb_row custom_padding=”0|0px|27px|0px|false|false” _builder_version=”3.22.3″][et_pb_column type=”3_5″ _builder_version=”3.19.18″][et_pb_text _builder_version=”3.19.18″ text_font=”||||||||” text_font_size=”15px” text_line_height=”1.8em” header_font=”||||||||”]
In a previous article in Moe Varua, I presented the results of another study during which we had found that juvenile Ature fish (amber stripe scad; Decapterus muroadsi) had ingested preferentially blue micro-plastics similar in size, shape and colour as their small planktonic prey. Experiments conducted in the laboratory at the Universidad Católica del Norte at Coquimbo in Chile revealed that micro-plastics(1mm long) ingested by juveniles of the Palm ruff fish (Seriolella violacea) remained on average one week, and up to seven weeks, in the fish’s gut. These results suggest that, under natural conditions, micro-plastics can stay long enough in a prey to be transferred to a predator that would eat and digest the prey. Para saber si los microplásticos son transferidos a los atunes a través sus presas, hemos analizados el tracto digestivo de 50 Kahi ave ave (yellow fin tuna, Thunnus albacares) and 43 Hahave (flying fish, Cheilopogon rapanouiensis), one of the most common prey of the tuna, captured along the coast of Rapa Nui by fishermen Hanga Piko y Hanga Roa in 2015 y 2016.
[/et_pb_text][/et_pb_column][et_pb_column type=”2_5″ _builder_version=”3.19.18″][et_pb_code _builder_version=”3.22.7″][bsa_pro_ad_space id=2][/et_pb_code][/et_pb_column][/et_pb_row][et_pb_row custom_padding=”0|0px|27px|0px|false|false” _builder_version=”3.22.3″][et_pb_column type=”2_5″ _builder_version=”3.19.18″][et_pb_image src=”https://moevarua.com/wp-content/uploads/2019/04/PreyInTuna_RapaNui2017FOTOnory.png” _builder_version=”3.19.18″][/et_pb_image][et_pb_image src=”https://moevarua.com/wp-content/uploads/2019/04/Microplastico.png” _builder_version=”3.19.18″][/et_pb_image][/et_pb_column][et_pb_column type=”3_5″ _builder_version=”3.19.18″][et_pb_text _builder_version=”3.19.18″ text_font=”||||||||” text_font_size=”15px” text_line_height=”1.8em” header_font=”||||||||”]We found micro-plastics in seven out of the 43 Hahave analysed. As found previously in Ature, a majority of the micro-plastics found in the Hahave were blue, similar in colour and size as small planktonic prey of the fish in the area This result confirms that planktivorous fish often ingest small plastic fragments. A single micro-plastic was found in the stomach of a Kahi ave ave meaning that, if micro-plastics are transferred to the tuna by their prey, small particles probably do not accumulate in the gut of such large fish. A single Kahi ave ave had three larger plastic fragments, between 15 and 26 mm long, in its stomach. These were probably ingested accidentally by the fish rather than transferred from its prey, which are too small to ingest such large items. These larger plastics presumably are too large to pass through the gut of a tuna, and they may thus remain in the stomach for a long time, potentially harming the fish. Nevertheless, only one out of the 50 tunas analysed had ingested meso-plastics.[/et_pb_text][/et_pb_column][/et_pb_row][/et_pb_section][et_pb_section fb_built=”1″ _builder_version=”3.22.3″ background_image=”https://moevarua.com/wp-content/uploads/2019/04/pescador-photo-Jaime-Aburto.jpg” custom_padding=”0|0|0|0px|false|false”][et_pb_row custom_padding=”39px|0px|0|0px|false|false” module_class=” et_pb_row_fullwidth” _builder_version=”3.22.3″ width=”89%” width_tablet=”80%” width_last_edited=”on|desktop” max_width=”89%” max_width_tablet=”80%” max_width_last_edited=”on|desktop” make_fullwidth=”on”][et_pb_column type=”4_4″ _builder_version=”3.19.18″][et_pb_text _builder_version=”3.19.18″ text_font=”||||||||” text_font_size=”15px” text_line_height=”1.8em”]Plastic contamination seems thus to not be an imminent threat for the populations of tunas along the coast of Rapa Nui, especially when compared with the impacts of overfishing by large vessel fleets offshore Rapa Nui. However, these encouraging results should not lessen the dramatic social, economic and ecological effects of micro-plastic contamination for Rapa Nui. There could be other, still unknown, effects of plastics on the fishes from Rapa Nui. For example, larvae or small juvenile fishes might be affected by ingestion of plastics. Significant efforts must be achieved in the a r e a s where the contamination originates to prevent plastic litter to enter the ocean and, subsequently, reach the shores of Rapa Nui. Initiatives to reduce plastic consumption, to encourage re-usable items, and to better manage plastic waste must be taken on urgently, both at an international and a national level. Also, laws to ban the discard of plastic litter at sea by fishing boats need to be implemented by, for example, monitoring plastic items before and after a fishing campaign, and sanctioning offenders. All these efforts to stop plastic contamination are essential in order to get our oceans clean again.[/et_pb_text][/et_pb_column][/et_pb_row][et_pb_row custom_padding=”93px|0px|397px|0px|false|false” _builder_version=”3.22.3″][et_pb_column type=”4_4″ _builder_version=”3.19.18″][et_pb_text _builder_version=”3.19.18″]
© Photo by
Jaime Aburto
[/et_pb_text][/et_pb_column][/et_pb_row][/et_pb_section][et_pb_section fb_built=”1″ _builder_version=”3.22.7″ custom_padding=”0px||0px|||”][et_pb_row custom_padding=”||0px|||” _builder_version=”3.22.7″ width_last_edited=”on|phone”][et_pb_column type=”4_4″ _builder_version=”3.22.7″][et_pb_text _builder_version=”3.22.7″ custom_padding=”||0px|||”][bsa_pro_ad_space id=1][/et_pb_text][/et_pb_column][/et_pb_row][/et_pb_section][et_pb_section fb_built=”1″ _builder_version=”3.22.7″ custom_padding=”3px||0px|||”][et_pb_row _builder_version=”3.22.7″][et_pb_column type=”4_4″ _builder_version=”3.22.7″][et_pb_text _builder_version=”3.22.7″]
Related Reports:
[/et_pb_text][et_pb_blog fullwidth=”off” posts_number=”3″ include_categories=”7″ show_date=”off” use_overlay=”on” _builder_version=”3.22.7″][/et_pb_blog][/et_pb_column][/et_pb_row][/et_pb_section]
