Fishing gear effects and ecology of the sea whip (<i>Halipteris willemoesi</i> (Cnidaria: Octocorallia: Pennatulacea)) in British Columbia, Canada: preliminary observations

Troffe, Peter M.; Levings, C. D.; Piercey, G. E.; Keong, Victor

doi:10.1002/aqc.685

Cited by 26 publications

(18 citation statements)

References 16 publications

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“…However, chronic and intensive effects of bottom trawling fishing, with habitat degradation are wellknown (Pusceddu et al, 2014), and the long-term exploitation of the Adriatic basin could have homogenized and simplified Adriatic soft bottoms habitats and species composition even in offshore areas. In particular, habitats formed by slow growing and long-lived specimens such as sea pens, hydroids, or corals, have a high vulnerability to fishing and even reduced fishing effort may cause considerable damage to these species, preventing their recovery (Troffe et al, 2005;Greathead et al, 2014). Moreover, the impacts of trawl fishing gears on the seabed differ depending on the sediment compositions and on bottom trawl target species (Pranovi et al, 2001(Pranovi et al, , 2005Eigaard et al, 2016).…”

Section: Discussionmentioning

confidence: 99%

Local Ecological Knowledge Indicates Temporal Trends of Benthic Invertebrates Species of the Adriatic Sea

et al. 2017

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In the Adriatic Sea, shifts in benthic community structure have been attributed to multiple stressors, from the effects of climate change to the impacts of commercial fishing. Some fishing practices, such as bottom trawling, have caused a widespread decline in exploited fish stocks. Bottom trawling is also expected to have negative impacts on benthic habitats, usually structured by and hosting a large array of invertebrate species, which provide important ecological services to fish and commercial invertebrate stocks. However, in contrast to commercial species for which long-term time series of the abundance exist, data on these habitat-forming invertebrates are scarce, as they are usually caught as bycatch and discarded. Therefore, there is great uncertainty about their long-term trends, and if these populations are stable or declining. Here we used interview surveys conducted with bottom-trawling fishers of the central Adriatic Sea to gather local ecological knowledge on megabenthos abundance occurring in their fishing domain, as an alternative source of information to conventional fisheries data. We interviewed 44 fishers, from the most important ports of the Marche region of Italy, to understand how megabenthic species have changed in abundance within the area since the 1980s. Specifically, we asked fishers to provide qualitative abundance scores for 18 invertebrate species in five phyla (Porifera, Cnidaria, Bryozoa, Mollusca, and Echinodermata) based on their recollection of these species' presence in bycatch. We stratified responses in homogeneous temporal periods and geographic sectors of the study area, and analyzed their response with mixed effect ordered logistic regression models in order to evaluate spatiotemporal changes in the perceived abundance of each species. Our analysis suggests that the abundance of the sponge Geodia cydonium, the molluscs Pecten jacobaeus, Atrina fragilis, Neopycnodonte cochlear, and the group of holothurians, have declined. From fishers' perceptions, only the bryozoan Amathia semiconvoluta has increased. Local ecological knowledge can provide important information on environmental change and can highlight species and ecosystems at risk when conventional scientific data are scarce or absent. This approach can be expanded to other regions of the Adriatic and broader Mediterranean Sea to reconstruct change of this heavily exploited marine region.

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Section: Discussionmentioning

confidence: 99%

Local Ecological Knowledge Indicates Temporal Trends of Benthic Invertebrates Species of the Adriatic Sea

et al. 2017

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“…and H. willemoesi, respectively. In British Columbia, Troffe et al (2005) found densities of juvenile (3 to 7 mm) H. willemoesi as high as 145 m -2 . The structure provided by sea whips may be important for enhancing prey availability and providing cover from predators.…”

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confidence: 99%

Response of the sea whip Halipteris willemoesi to simulated trawl disturbance and its vulnerability to subsequent predation

Malecha¹,

Stone²

2009

Mar. Ecol. Prog. Ser.

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The sea whip Halipteris willemoesi occurs in habitats coincident with bottom trawl fisheries in the Gulf of Alaska and Bering Sea and can be damaged by passing trawls. Little is known about the long-term fate of sea whips damaged by trawl gear. Sea whip responses to simulated trawl disturbance were observed in situ over a period of about 1 yr in order to assess delayed mortality from sublethal injuries. Colonies of H. willemoesi were randomly assigned to 3 treatment groups and 1 control group. Treatments were designed to mimic trawl damage including dislodgement, fracture of the axial rod, and soft tissue abrasion. Fifty percent of dislodged colonies demonstrated the ability to rebury their peduncles and recover to an erect position. Most of these colonies eventually became dislodged again without further disturbance and only one was erect at the final observation. None of the fractured colonies were able to repair their axial rods and only one was erect at the experiment's conclusion. Light tissue abrasion caused only minor tissue losses that lessened over time, and all abraded and control colonies remained erect throughout the experiment. Tissue losses among the dislodged and fractured sea whips increased throughout the experimental period and were mainly due to predation by the nudibranch Tritonia diomedea, which appeared to react with a strong scavenging response to sea whips lying on the seafloor. The presence of predators in areas where sea whips are disturbed may exacerbate trawl effects since damaged or dislodged colonies are more vulnerable to predation. 388: 197-206, 2009 entire shelf averaged 2.4% swept annually, but in the Bering Sea and Gulf of Alaska many areas were trawled more than 5 times per year and one area was trawled 17 times per year (Rose & Jorgensen 2005). Similar intensities have been reported for heavily trawled areas on both sides of the Atlantic Ocean (Floderus & Pihl 1990, Auster et al. 1996. KEY WORDS: Trawling · Sea whip · Halipteris willemoesi · Seafloor habitat · Nudibranch · Tritonia diomedea Resale or republication not permitted without written consent of the publisherMar Ecol Prog SerSea whips have a relatively simple morphology consisting of a bulbous basal peduncle (which serves as an anchor in soft sediments) and a vertical rachis or shaft extending distally from the peduncle. An axial rod, composed of magnesium calcite, supports the entire colony, and the rachis is populated with rows of polyps. Ten species of pennatulaceans are known to occur in Alaska (Stone & Shotwell 2007) and size varies considerably among species. Halipteris willemoesi Kölliker, 1870(von Kölliker 1870 can reach heights greater than 300 cm (Stone & Shotwell 2007), while Protoptilum sp. may reach just 35 cm. Sea whips can form dense groves that provide vertical structure to low relief habitats. In Alaska, Stone et al. (2005) found densities at least as high as 16 and 6 m -2 for adult specimens of Protoptilum sp. and H. willemoesi, respectively. In British Columbia, Troffe et al. (2005) f...

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“…Due to their formation of biogenic habitat and poor recovery after fishing disturbance (Greathead et al 2005;Troffe et al 2005;Heifetz et al 2009;Malecha & Stone 2009), sea pen concentrations are considered Vulnerable Marine Ecosystems (VMEs) (FAO 2009) in the North-west Atlantic, and the Northwest Atlantic Fisheries Organization (NAFO) has closed several areas to bottom-contact fishing gear on Flemish Cap to protect the sea pens there (NAFO 2017). In Canada, sea pen fields are considered Ecological or Biological Significant Areas (EBSAs; Kenchington 2014), as well as Significant Benthic Areas (DFO 2017) that require special management consideration.…”

Section: Introductionmentioning

confidence: 99%

Morphometry and growth of sea pen species from dense habitats in the Gulf of St. Lawrence, eastern Canada

Murillo

MacDonald

Kenchington

et al. 2018

Marine Biology Research

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We examined four species of sea pen (Anthoptilum grandiflorum, Halipteris finmarchica, Pennatula aculeata and Pennatula grandis) collected from the Gulf of St. Lawrence and mouth of the Laurentian Channel, eastern Canada. An exponential length-weight relationship was found for all four species, where growth in weight was progressively greater than growth in length with increasing colony size. Halipteris finmarchica, P. grandis and P. aculeata presented the better allometric fits, explaining over 80% of the variance. In addition, a count of growth increments visible in transverse sections in 86 A. grandiflorum and 80 P. aculeata samples was made. Presumed ages ranged between 5 and 28 years for A. grandiflorum and 2 and 21 years for P. aculeata. Radiocarbon assays were inconclusive and could not be used to confirm these ages; further age validation is required. Radial growth of the rod is slow during the first years, increasing at intermediate sizes of the colony and slowing down again for large colonies. Similar results were obtained from the relationship between colony length and number of growth increments where a logistic model was the best fit to the data. On average Spearman's rank correlations showed 11% of shared variance between sea pen length or weight and environmental variables. Bottom temperature and salinity, depth and summer primary production were significantly correlated to sea pen size for most species. ARTICLE HISTORY

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Fishing gear effects and ecology of the sea whip (Halipteris willemoesi (Cnidaria: Octocorallia: Pennatulacea)) in British Columbia, Canada: preliminary observations

Cited by 26 publications

References 16 publications

Local Ecological Knowledge Indicates Temporal Trends of Benthic Invertebrates Species of the Adriatic Sea

Local Ecological Knowledge Indicates Temporal Trends of Benthic Invertebrates Species of the Adriatic Sea

Response of the sea whip Halipteris willemoesi to simulated trawl disturbance and its vulnerability to subsequent predation

Morphometry and growth of sea pen species from dense habitats in the Gulf of St. Lawrence, eastern Canada

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