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Home , Hapuku, Paua

Quarterly report of investigations of suspected exotic marine and freshwater pests and diseases: April to June 2019

Range extension of non- notifier had also received information tested had recently spawned. indigenous red alga that more paua had washed up further Spawning is known to be a stressful event along the beach. No other organisms in and increases their metabolic confirmed appeared to be affected. All paua had demand. It was considered possible Council contacted MPI after been scavenged, so that only empty that the mortality was related to a large drift of red alga that was washed shells remained. a lack of sufficient food, spawning and ashore at Red Beach and Orewa, north possibly other undetected environmental A week later a further report of paua of Auckland, was identified asSolieria factors, rather than a disease process. The mortalities in the area was received, sp. (Rhodophyta: Solieriaceae) by a investigation was stood down. NIWA expert, who received a sample and this time samples were able to be from a member of the public. This is a collected and sent to the MPI mortality, non-indigenous red alga that was first Health Laboratory (AHL). Tests were Horowhenua negative for Perkinsus spp., viral reported from in 1992, A mass shellfish mortality on Waiterere, ganglioneuritis virus and withering and until now was only known from Hokio and Waikawa Beaches in syndrome. Unfortunately the paua Manukau Harbour, Kaipara Harbour and Horowhenua was reported to MPI. were too decomposed for histological the Orakei Basin (Nelson et al., 2015). Its Meteorological data showed that there examination. detection in the northern Hauraki Gulf was heavy rain and a temperature drop represents a significant range extension. The most significant finding was the just prior to the notification, although It can become a nuisance when it forms accumulation of abundant gravel sea-surface temperatures remained high. dense mats that may wash ashore or and sand within the lumen of the At first, Horizons Council and MPI were clog commercial fishers’ nets (Nelson et digestive tract of specimens examined. unable to find live samples for disease al., 2015). Reproductive structures have This suggested there may have been testing, but noted that 95 percent of the never been found in samples of the alga significant turbulence in the water affected shells were the clamDosinia when examined, so identification beyond column, which could have reduced the anus (: Heterodonta), and genus has not yet been possible. The availability of food and/or the ability of that tuatuas ( subtriangulata) range extension was added to the Marine the paua to feed adequately and avoid appeared unaffected. Invasives Taxonomic Service records and ingesting gravel and sand. This area of A third visit was successful in locating the investigation was stood down. the beach had also experienced increased live Dosinia, and these were submitted sedimentation when the Hapuku River to the AHL for disease testing. A high Range extension of changed course after the 2016 Kaikoura level of tissue breakdown alongside non-indigenous hydroid earthquake, and is known to experience bacterial growth was detected, and all strong swells that can move boulders and confirmed samples had recently spawned. Bacteria, dislodge paua from the substrate. The non-indigenous hydroid Ectopleura post-spawning stress and thermal stress crocea (Cnidaria: Tubulariidae) It was concluded that the paua caused by high sea-surface temperatures was collected during an Auckland mortalities were likely to be associated may have collectively caused disease in Council marine pest survey of the with an environmental stress rather than this population. Alternatively, thermal Kaipara Harbour. This represents a disease, and the investigation was and post-spawning stress may have a range extension for this species, stood down. predisposed them to bacterial infection. which previously has been recorded from Tauranga, New Plymouth, Tuatua mortality, Northland It was agreed that more samples should Lyttelton, Whangarei, Dunedin, Picton, An increase in the number of dead be tested, and these were taken about a Wellington, Nelson and Manukau. tuatua (Paphies subtriangulata) (Bivalvia: month after the event was first reported Mesodesmatidae) and empty tuatua (and about 3 weeks after the first Paua mortality, Kaikoura shells (predominantly large individuals) samples had been received). Like the A scientist from the Paua Industry on Ninety Mile Beach was reported to first samples, the second lot were also Council contacted MPI to report MPI. Samples were submitted to the mostly post-spawning animals, but the mortality in wild black-foot paua AHL to test for disease. Overall, the majority appeared to be in good body ( iris) (: Haliotidae) animals appeared to be in fair body condition and did not have the same at Mangamaunu Bay, near Kaikoura. condition and there were no signs of an level of tissue breakdown as previously During the previous week a number of infectious agent. Scattered Rickettsia- seen. This may indicate that they were dead paua had washed ashore, and the like organisms (RLOs) were present recovering, or had not been exposed to notifier was concerned that the mortality but it was uncertain whether they were the same organisms or stressors as the rate appeared to be increasing. The significant. Histology showed that the first samples.

Surveillance 46 (3) 2019 | 67 It was concluded that this mortality NIWA obtained samples and subjected during the ’ normal feeding was likely multi-factorial, and stressors them to molecular analysis, and the activities. While they could not be such as unfavourable environmental result was a 100 percent match with identified to species, a number of local conditions and/or spawning may have a sample of B. hamifera from Japan. species are known to occur and several been involved. Testing ruled out any The native range of this species is the are undescribed. It was concluded that primary pathogens as a cause, so the northwest Pacific (D’Archino & Nelson, these species were unlikely to be exotic, investigation was stood down. 2019). After taxonomist evaluation, this and the investigation was stood down. species does not appear to be invasive, so New to New Zealand no further response was recommended. New to New Zealand species, Northland amphipod investigated Two horned blennies, Parablennius Dogfish mortality NIWA notified MPI following the intermedius (: Blenniidae), investigated identification of what appeared to be were seen on a wharf pile at Te Hapua A member of the public notified MPI a new to New Zealand amphipod, Wharf, Parengarenga Harbour. This after seeing 20–30 dead fish, which he Hirayamia mortonii (Crustacea: species has not previously been reported suspected were spiny dogfish Squalus( Amphipoda). A single female specimen in New Zealand. The two fish were seen acanthias) (Chondrichthyes: Squalidae), had been collected by Environment on two successive days at a depth of 2 while walking on Peka Peka Beach, Canterbury during an intertidal survey at metres on the same piles by NIWA divers Kāpiti. The fish were along the tideline Robinsons Bay, Akaroa Harbour, in 2017, during a recreational diving trip. None and had been heavily scavenged by but was only recently identified. The were seen at Te Pau Wharf, about 3 nm seagulls. Fisheries New Zealand was taxonomist was 90 percent certain of the away. No specimens were collected and contacted because this incident could be identification, but examination of both the species was identified from photos. the result of by-catch dumping. Fisheries male and female specimens is required to validate this species Parablennius spp. (known collectively officers attended and confirmed that the as combtooth blennies) are found in fish were spiny dogfish. Under certain H. mortonii is native to the Hong Kong the Atlantic, western Pacific and Indian reporting conditions, commercial fishers region of the South China Sea. It is in the . P. intermedius, commonly are allowed to discard dogfish by-catch. subfamily Corophiinae, of which four known as the horned blenny, is native It was concluded that these fish were species in two genera have already been to the southwest Pacific and most likely discarded by-catch, and no reported from New Zealand. Many species has been reported from northern infectious disease was involved, so the are well-known biofoulers of hard surfaces, Queensland to southern New South investigation was stood down. including vessel hulls and harbour Wales in , as well as New Worms in blue structures. They are mostly known from Caledonia and the Solomon Islands. the northern hemisphere, but some species Adults are found in subtropical investigated have become well established in equivalent estuaries and coastal bays, typically Fisheries New Zealand staff were southern hemisphere environments, likely occupying shallow water (0–10 metres). notified by a commercial fish processor arriving as hitchhikers on vessel hulls It is possible this species could become that unusual worms had been found in (Fenwick, 2019). established (if it is not already) in the the gut of (Parapercis colias) While this species has not previously subtropical conditions of northern New (Actinopterygidae: ) caught been recorded outside its native range, Zealand. This species does not have an at the Chatham Islands. Fish stomachs the wide distribution of other members of invasive history, so no further action was were full of fine, hair-like worms, and this family may suggest that a population recommended and the investigation was there was concern that when the fish of H. mortonii could establish in New stood down. were processed they could contaminate Zealand. There is also the possibility the product. The worms had not been that H. mortonii may already be New to New Zealand observed before by the processor, and established in New Zealand and may seaweed species, Otago blue cod caught from several locations have a wider distribution than already NIWA notified MPI that one of appeared to be affected. thought, as it is difficult to distinguish its algal taxonomists had found Worms from the gut contents were from Paracorophium excavatum (a a new to New Zealand seaweed, collected and submitted to the Marine closely related and similar-looking Bonnemaisonia hamifera (Rhodophyta: Invasives Taxonomic Service for native amphipod) without consulting an Bonnemaisoniaceae), at Waikouaiti examination, where they were identified amphipod expert (Fenwick, 2019). Its Estuary, Otago. An unusual bloom had as belonging to the genus Eunice. The likely impact in New Zealand is unknown, been initially observed by members of samples were in fairly good condition especially as there are no published the public, and NIWA had responded to apart from being slightly digested. They records from outside its native range. photos uploaded to the internet. did not appear to be reproductive, and However, presumably it could compete were likely ingested from the benthos with or displace other native amphipods 68 | Surveillance 46 (3) 2019 that share similar habitats, such as Histology showed no evidence of an where it was identified as Trichomusculus P. excavatum (Fenwick, 2019). infectious process, so the “spots” were barbatus. This species is native to New unlikely to be due to a primary pathogen. Zealand and widely distributed. As there Response options to manage a small, Histology did, however, show some was no biosecurity risk, the investigation mobile are few. There is abnormalities that could be associated was stood down. limited information on its potential with heat and/or other stress, or a impact in New Zealand, and it could toxin. It was concluded that the lesions Toheroa mortality already be established or more were more likely to be associated with investigated widespread in New Zealand than environmental stress than a disease, and A mortality event involving toheroa originally thought, owing to its similarity the investigation was stood down. () (Bivalvia: to the native P. excavatum. Therefore no Mesodesmatidae) along Ninety Mile further response was recommended and Pipi decline investigated beach was reported to MPI. Samples the investigation was stood down. A member of the public reported collected and sent to the AHL were Rainbow trout with lesions to MPI that pipi () found to be in good body condition, investigated (Bivalvia: Mesodesmatidae) were dying with well-developed reproductive tissue. or displaying ill-health near Marsden There was no evidence of significant Fish & Game Otago notified MPI after Cove, Whangarei Harbour. The Incursion inflammation or tissue breakdown. a member of the public brought in a Investigator (II) requested that specimens No cause of the mortality event was rainbow trout (Oncorhynchus mykiss) be sent to MPI’s AHL for exotic disease apparent in the animals examined. With (Actinopterygii: Salmonidae) with testing and presence of RLOs. The no evidence of a biosecurity issue, the lesions around the gills. It had been Northland Regional Council advised that investigation was stood down. line-caught in a reservoir and had lesions there had been no adverse environmental around the gills. or pollution events in the area. Eel mortality investigated A member of the public contacted MPI Only one fish was reported, although Tests found no evidence of exotic disease, after noticing dead eels (Anguilla sp.) in another similar case had been reported and no significant abnormalities were a stream in the Hutt Valley, Wellington. to Fish & Game 2 years ago from the seen on macroscopic examination. Light Three dead eels were found on the day same catchment. Reservoir water to moderate infection of RLOs was found of the notification, and four more the levels were reportedly high and fishing in most of the specimens. RLOs are following day. The Hutt City Council activities had been otherwise normal. commonly found in shellfish mortalities, was notified and conducted a site visit. but their significance is unknown. They The fish was tested for exotic diseases At least three more dead eels were found were found in gill and digestive tract at the AHL. It tested negative to upstream from the initial site, bringing tissue, where they could compromise Aphanomyces invadans, Yersinia ruckeri, the total to 10 eels. Nothing of concern the ability of animals to respire and Aeromonas salmonicida and Lactococcus was noted in terms of stream health. digest food. However, it was noted that garvieae. No other cases were reported, The stream did appear to have a reduced specimens were undergoing gonad and the investigation was stood down. flow, but it was not stagnant. This stream reabsorption, a metabolically stressful It was concluded that the lesions were is considered a drain, and historically event. This process, in combination with most likely due to injury and a secondary was fed by water pumped from a bore high sea temperatures and the presence bacterial infection. situated close upstream. The pump had of RLOs, could stress the animals and apparently failed a few years ago and Brown trout with lesions weaken the population. Alternatively, was never replaced, so the stream only the combination of high sea temperature investigated flowed when there was sufficient rain and the metabolic stress described could Since late 2018 a local angler had been to sustain it. One of two eels collected predispose the animals to RLO infection. catching brown trout (Salmo trutta) by an II was in suitable condition for As no exotic disease was detected the (Actinopterygii: Salmonidae) with histopathological examination at the investigation was closed. unusual spots on them in the Taieri AHL. An accumulation of iron within catchment. He had noticed an increase Suspected exotic mollusc the tissues and cells was noted. This in the prevalence of affected fish, from an investigated can be a secondary effect of increased estimated 40 percent to about 60 percent. red blood cell breakdown, increased MPI was contacted by a marine He informed Fish & Game Otago, who dietary iron, or exposure to chemicals scientist after a suspect Asian date notified MPI. A single fish presented or other metals that may cause bio- (Arcuatula senhousia) (Bivalvia: with areas of haemorrhage on the accumulation of iron. Parasites (similar ) was found in a core sample skin, the sclera of both eyes, pelvic to apicomplexans) were found in the collected in the Marlborough Sounds. and pectoral fins. It tested negative at macrophages in the blood cavities of The preserved specimen was sent to the the AHL for RLOs and Lactococcus organs, but their significance could not Marine Invasives Taxonomic Service, garviae (both present in New Zealand). be determined. As only one eel was Surveillance 46 (3) 2019 | 69 suitable for examination, it was not References Nelson WA, Neill KF, D’Archino R (2015). When possible to determine whether these seaweeds go bad: an overview of outbreaks of D’Archino R, Nelson W (2019). Bonnemaisonia nuisance quantities of marine macroalgae in factors were common to all affected eels. hamifera Har. collected in Karitane, Otago, New Zealand, New Zealand Journal of Marine The cause of the mortalities remains New Zealand. Marine Exotic Species Note 102. and Freshwater Research 49(4) 472–491. DOI: uncertain, but environmental factors that National Institute of Water and Atmospheric 10.1080/00288330.2015.1064975 went undetected at the time may have Research, New Zealand. also contributed. No further dead eels Cox SA, Francis M (2019). Notes on the were reported, so the investigation was Australian blenny Parablennius intermedius (J.D. Rissa Williams stood down. Ogilby, 1915), collected from Parengarenga Incursion Investigator (Marine) Harbour, New Zealand. Marine Exotic Species Surveillance & Incursion Investigation Note 101. National Institute of Water and (Aquatic and Environment Health) Atmospheric Research, New Zealand. Diagnostic and Surveillance Directorate Fenwick G (2019). Notes on the Japanese Biosecurity New Zealand amphipod Hirayamaia mortonii (Hirayama, Ministry for Primary Industries 1986), collected from Akaroa Harbour, New [email protected] Zealand. Marine Exotic Species Note 103. National Institute of Water and Atmospheric Research, New Zealand.

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